The Collaborative International Dictionary of English v.0.48:

Series \Se"ries\, n. [L. series, fr. serere, sertum, to join or
   bind together; cf. Gr. ??? to fasten, Skr. sarit thread. Cf.
   Assert, Desert a solitude, Exert, Insert,
   Seraglio.]
   1. A number of things or events standing or succeeding in
      order, and connected by a like relation; sequence; order;
      course; a succession of things; as, a continuous series of
      calamitous events.
      [1913 Webster]

            During some years his life a series of triumphs.
                                                  --Macaulay.
      [1913 Webster]

   2. (Biol.) Any comprehensive group of animals or plants
      including several subordinate related groups.
      [1913 Webster]

   Note: Sometimes a series includes several classes; sometimes
         only orders or families; in other cases only species.
         [1913 Webster]

   3. (Bot.) In Engler's system of plant classification, a group
      of families showing certain structural or morphological
      relationships. It corresponds to the cohort of some
      writers, and to the order of many modern systematists.
      [Webster 1913 Suppl.]

   4. (Math.) An indefinite number of terms succeeding one
      another, each of which is derived from one or more of the
      preceding by a fixed law, called the law of the series;
      as, an arithmetical series; a geometrical series.
      [1913 Webster]

   5. (Elec.) A mode of arranging the separate parts of a
      circuit by connecting them successively end to end to form
      a single path for the current; -- opposed to parallel.
      The parts so arranged are said to be

   in series.
      [Webster 1913 Suppl.]

   6. (Com.) A parcel of rough diamonds of assorted qualities.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

series
    n 1: similar things placed in order or happening one after
         another; "they were investigating a series of bank
         robberies"
    2: a serialized set of programs; "a comedy series"; "the
       Masterworks concert series" [syn: serial, series]
    3: a periodical that appears at scheduled times [syn: series,
       serial, serial publication]
    4: (sports) several contests played successively by the same
       teams; "the visiting team swept the series"
    5: (electronics) connection of components in such a manner that
       current flows first through one and then through the other;
       "the voltage divider consisted of a series of fixed
       resistors"
    6: a group of postage stamps having a common theme or a group of
       coins or currency selected as a group for study or
       collection; "the Post Office issued a series commemorating
       famous American entertainers"; "his coin collection included
       the complete series of Indian-head pennies"
    7: (mathematics) the sum of a finite or infinite sequence of
       expressions

Moby Thesaurus II by Grady Ward, 1.0:

148 Moby Thesaurus words for "series":
   Indian file, alternation, array, arsis, articulation, back number,
   bank, battery, beat, biotype, block, bout, branch, buzz, category,
   catena, catenation, chain, chain reaction, chaining, chasing,
   circle, circuit, class, collection, column, coming after,
   concatenation, connection, consecution, consecutiveness,
   continuance, continuation, continuity, continuum, copy, course,
   cycle, descent, diastole, dogging, downbeat, drone, edition,
   endless belt, endless round, extension, family, file, filiation,
   following, gamut, genotype, genus, geometrical progression,
   gradation, group, heeling, hounding, hum, impression, issue,
   kingdom, kit, library, library edition, line, lineage,
   logical sequence, monotone, nexus, number, order,
   order of succession, outfit, pack, pendulum, periodicity, phylum,
   plenum, posteriority, postposition, powder train, printing,
   procession, progression, prolongation, pulse, pursual, pursuance,
   pursuit, queue, range, rank, recurrence, reticulation, revolution,
   rotation, round, routine, row, run, scale, school edition, section,
   sequel, sequence, set, shadowing, single file, species, spectrum,
   spell, string, subclass, subfamily, subgenus, subjunction,
   subkingdom, suborder, subspecies, subtribe, succession,
   successiveness, suffixation, suit, suite, superclass, superfamily,
   superorder, superspecies, swath, systole, tailing, thesis, thread,
   tier, trade book, trade edition, trailing, train, tribe, turn,
   upbeat, variety, volume, wheel, windrow