The Collaborative International Dictionary of English v.0.48:

Study \Stud"y\, n.; pl. Studies. [OE. studie, L. studium, akin
   to studere to study; possibly akin to Gr. ? haste, zeal, ? to
   hasten; cf. OF. estudie, estude, F. ['e]tude. Cf. Etude,
   Student, Studio, Study, v. i.]
   1. A setting of the mind or thoughts upon a subject; hence,
      application of mind to books, arts, or science, or to any
      subject, for the purpose of acquiring knowledge.
      [1913 Webster]

            Hammond . . . spent thirteen hours of the day in
            study.                                --Bp. Fell.
      [1913 Webster]

            Study gives strength to the mind; conversation,
            grace.                                --Sir W.
                                                  Temple.
      [1913 Webster]

   2. Mental occupation; absorbed or thoughtful attention;
      meditation; contemplation.
      [1913 Webster]

            Just men they seemed, and all their study bent
            To worship God aright, and know his works. --Milton.
      [1913 Webster]

   3. Any particular branch of learning that is studied; any
      object of attentive consideration.
      [1913 Webster]

            The Holy Scriptures, especially the New Testament,
            are her daily study.                  --Law.
      [1913 Webster]

            The proper study of mankind is man.   --Pope.
      [1913 Webster]

   4. A building or apartment devoted to study or to literary
      work. "His cheery little study." --Hawthorne.
      [1913 Webster]

   5. (Fine Arts) A representation or rendering of any object or
      scene intended, not for exhibition as an original work of
      art, but for the information, instruction, or assistance
      of the maker; as, a study of heads or of hands for a
      figure picture.
      [1913 Webster]

   6. (Mus.) A piece for special practice. See Etude.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Study \Stud"y\, v. i. [imp. & p. p. Studied; p. pr. & vb. n.
   Studying.] [OE. studien, OF. estudier, F. ['e]tudier. See
   Study, n.]
   1. To fix the mind closely upon a subject; to dwell upon
      anything in thought; to muse; to ponder. --Chaucer.
      [1913 Webster]

            I found a moral first, and then studied for a fable.
                                                  --Swift.
      [1913 Webster]

   2. To apply the mind to books or learning. --Shak.
      [1913 Webster]

   3. To endeavor diligently; to be zealous. --1 Thes. iv. 11.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Study \Stud"y\, v. t.
   1. To apply the mind to; to read and examine for the purpose
      of learning and understanding; as, to study law or
      theology; to study languages.
      [1913 Webster]

   2. To consider attentively; to examine closely; as, to study
      the work of nature.
      [1913 Webster]

            Study thyself; what rank or what degree
            The wise Creator has ordained for thee. --Dryden.
      [1913 Webster]

   3. To form or arrange by previous thought; to con over, as in
      committing to memory; as, to study a speech.
      [1913 Webster]

   4. To make an object of study; to aim at sedulously; to
      devote one's thoughts to; as, to study the welfare of
      others; to study variety in composition.
      [1913 Webster]

            For their heart studieth destruction. --Prov. xxiv.
                                                  2.
      [1913 Webster]

WordNet (r) 3.0 (2006):

study
    n 1: a detailed critical inspection [syn: survey, study]
    2: applying the mind to learning and understanding a subject
       (especially by reading); "mastering a second language
       requires a lot of work"; "no schools offer graduate study in
       interior design" [syn: study, work]
    3: a written document describing the findings of some individual
       or group; "this accords with the recent study by Hill and
       Dale" [syn: report, study, written report]
    4: a state of deep mental absorption; "she is in a deep study"
    5: a room used for reading and writing and studying; "he knocked
       lightly on the closed door of the study"
    6: a branch of knowledge; "in what discipline is his
       doctorate?"; "teachers should be well trained in their
       subject"; "anthropology is the study of human beings" [syn:
       discipline, subject, subject area, subject field,
       field, field of study, study, bailiwick]
    7: preliminary drawing for later elaboration; "he made several
       studies before starting to paint" [syn: sketch, study]
    8: attentive consideration and meditation; "after much
       cogitation he rejected the offer" [syn: cogitation,
       study]
    9: someone who memorizes quickly and easily (as the lines for a
       part in a play); "he is a quick study"
    10: a composition intended to develop one aspect of the
        performer's technique; "a study in spiccato bowing"
    v 1: consider in detail and subject to an analysis in order to
         discover essential features or meaning; "analyze a sonnet
         by Shakespeare"; "analyze the evidence in a criminal
         trial"; "analyze your real motives" [syn: analyze,
         analyse, study, examine, canvass, canvas]
    2: be a student; follow a course of study; be enrolled at an
       institute of learning
    3: give careful consideration to; "consider the possibility of
       moving" [syn: study, consider]
    4: be a student of a certain subject; "She is reading for the
       bar exam" [syn: learn, study, read, take]
    5: learn by reading books; "He is studying geology in his room";
       "I have an exam next week; I must hit the books now" [syn:
       study, hit the books]
    6: think intently and at length, as for spiritual purposes; "He
       is meditating in his study" [syn: study, meditate,
       contemplate]

Moby Thesaurus II by Grady Ward, 1.0:

532 Moby Thesaurus words for "study":
   Nachtmusik, Pap test, Walter Mitty, absence of mind,
   absolute music, absorbed attention, absorption, abstractedness,
   abstraction, academic discipline, academic specialty, adaptation,
   advisement, aim, air, air varie, airing, aleatory, aleatory music,
   ambition, analysis, analyze, anatomic diagnosis, animus,
   application, applied science, area, arena, arrangement, art,
   art object, article, aspiration, atelier, attend to business,
   autopsy, be abstracted, be alert, be determined, be obsessed with,
   bemusement, biological diagnosis, biopsy, black and white, bone,
   boning, booking office, box office, brainchild, brainwork, branch,
   branch office, bric-a-brac, brood, brooding, brouillon,
   brown study, buzz session, cabinet, canvass, canvassing, cartoon,
   castle-building, causerie, chamber music, chamber orchestra,
   chambers, chancellery, chancery, charcoal, charcoal drawing, check,
   check out, check over, check up, check up on, chew over,
   chew the cud, chiaroscuro, classic, classical education,
   clinical diagnosis, close study, closet, colloquium, comment upon,
   commit to memory, commitment to memory, composition, con,
   concentrate on, concentration, concern, conference, conning,
   consider, consideration, consulate, contemplate, contemplation,
   contemplativeness, controvert, core curriculum,
   corporate headquarters, counsel, course, course of study, cram,
   cramming, crayon, creation, curriculum, cytodiagnosis, daydream,
   daydreamer, daydreaming, deal with, debate, debating, deep study,
   deep thought, deliberate, deliberate upon, deliberation,
   delineation, den, department of knowledge, depth of thought,
   descant, desideration, desideratum, design, desire, determination,
   diagnosis, diagram, dialectic, dialogue, differential diagnosis,
   dig, digest, digital examination, discipline, discourse,
   discourse about, discuss, discussion, disquisition, dissertation,
   domain, doodle, draft, drawing, dream, dreaming, drill, ebauche,
   effect, elective, electrocardiography, electroencephalography,
   electromyography, electronic music, elucubrate, embassy, endeavor,
   engagement, engrossment, enquiry, esquisse, essay, etude,
   examination, examine, exchange of views, exchange views,
   excogitate, excursus, executive office, exercise,
   exercise of memory, exploration, exposition, extensive study,
   fantasy, fantasying, feature, field, field of inquiry,
   field of study, first approach, fit of abstraction, fix on,
   fixed purpose, flashback, focus on, forum, function,
   general education, general studies, get by heart,
   get letter-perfect, give an examination, give heed, go into,
   go over, graph, grind, grinding, grotesque, handle, harmonization,
   haunt, have by heart, headquarters, headwork, heed, hindsight,
   home office, homily, humanities, idea, immersion, incidental music,
   inquiry, inspect, inspection, instrumental music, intendment,
   intent, intention, intentness, introductory study, introspect,
   invention, investigate, investigation, involvement,
   joint discussion, kitsch, knock around, know by heart, labor,
   laboratory diagnosis, learn about, learn by heart, learn verbatim,
   learning, learning by heart, legation, lesson, lessons,
   liberal arts, library, line drawing, loft, logical analysis,
   logical discussion, look at, look lively, look out, look over,
   look sharp, looking back, lucubrate, lucubration, main office,
   major, mammography, master, masterpiece, masterwork, meaning,
   meditate, meditation, melancholy, memoir, memorization, memorize,
   memorizing, mental labor, mind, minor, miss nothing, mobile,
   monitor, monograph, monomania, mooning, moonraking, morceau,
   motive, mull over, muse, muse on, musefulness, museum piece,
   musing, muted ecstasy, natural science, nisus, nocturne, note,
   nude, observe, obsession, office, old master, ology,
   open discussion, open forum, opus, oral examination, orchestration,
   outline, overhaul, overhauling, overlook, pandect,
   panel discussion, paper, paragraph, parrot, pass over,
   pass under review, pastel, pasticcio, pastiche, pay attention,
   pay heed, peer at, pen-and-ink, pencil drawing, pensiveness,
   perlustration, perpend, perusal, peruse, physical diagnosis,
   physical examination, piece, piece of virtu, pipe dream,
   pipe-dreaming, plan, play around with, play with, plunge into,
   point, ponder, pondering, pore over, postmortem,
   postmortem diagnosis, practice, preliminary study, preoccupation,
   production, profound thought, program music, project, prolegomenon,
   proposal, proseminar, prospectus, province, pure science, purpose,
   quadrivium, quality control, rap, rap session, rapt attention,
   read, reading, reason, reason about, reason the point, recall,
   recalling, recite, recollecting, recollection, reconsideration,
   reflect, reflection, reflectiveness, refresher course,
   regard studiously, remembering, remembrance, reminiscence, repeat,
   repeat by heart, research, research paper, resolution, resolve,
   restudy, restudying, retreat, retrospect, retrospection, reverie,
   review, revolving, ricercar, rote, rote memory, rough copy,
   rough draft, rough outline, ruminate, rumination, run over,
   run-through, sail loft, sake, sanctum sanctorum, scan, science,
   scientific education, score, screed, scrutinize, scrutiny, seek,
   seminar, serodiagnosis, set an examination, shop, sift, silhouette,
   silver-print drawing, single-mindedness, sinopia, size, size up,
   sketch, smear, social science, sonata, sonatina, special article,
   specialty, speculate, speculation, speculativeness, sphere,
   stabile, stacks, stargazing, statue, still life, strain,
   string orchestra, string quartet, strive, striving, struggle,
   studio, studiousness, studying, subdiscipline, subject, submersion,
   survey, swat, swatting, sweat, sweat blood, swot, swot up,
   swotting, symposium, take care, take heed, take stock of,
   take the measure, take up, talk, talk about, talk of, talk over,
   technical education, technicology, technics, technology,
   term paper, test, theme, theme and variations, thesis, think about,
   think over, thoughtfulness, thresh out, ticket office,
   town meeting, toy with, tracing, tract, tractate, trance, treat,
   treatise, treatment, trio, trivium, turn over, urinalysis,
   uroscopy, variation, ventilate, ventilation, vet, view, vignette,
   virtu, visitation, wade through, watch out, weigh, weighing,
   wide reading, will, wistfulness, woolgathering, work, work of art,
   work-up, workroom