The Collaborative International Dictionary of English v.0.48:

Hymn \Hymn\ (h[i^]m), n. [OE. hympne, ympne, F. hymne, OF. also
   ymne, L. hymnus, Gr. ?; perh. akin to ? web, ? to weave, and
   so to E. weave.]
   An ode or song of praise or adoration; especially, a
   religious ode, a sacred lyric; a song of praise or
   thanksgiving intended to be used in religious service; as,
   the Homeric hymns; Watts' hymns.
   [1913 Webster]

         Admonishing one another in psalms and hymns. --Col.
                                                  iii. 16.
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         Where angels first should practice hymns, and string
         Their tuneful harps.                     --Dryden.
   [1913 Webster]

   Hymn book, a book containing a collection of hymns, as for
      use in churches; a hymnal.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hymn \Hymn\, v. t. [imp. & p. p. Hymned; p. pr. & vb. n.
   Hymning.] [Cf. L. hymnire, Gr. ?.]
   To praise in song; to worship or extol by singing hymns; to
   sing.
   [1913 Webster]

         To hymn the bright of the Lord.          --Keble.
   [1913 Webster]

         Their praise is hymned by loftier harps than mine.
                                                  --Byron.
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The Collaborative International Dictionary of English v.0.48:

Hymn \Hymn\, v. i.
   To sing in praise or adoration. --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hymn
    n 1: a song of praise (to God or to a saint or to a nation)
         [syn: hymn, anthem]
    v 1: sing a hymn
    2: praise by singing a hymn; "They hymned their love of God"

Moby Thesaurus II by Grady Ward, 1.0:

121 Moby Thesaurus words for "hymn":
   Agnus Dei, Benedicite, Gloria, Gloria Patri, Gloria in Excelsis,
   Introit, Magnificat, Miserere, Negro spiritual, Nunc Dimittis,
   Te Deum, Trisagion, Vedic hymn, acknowledgment, alleluia, answer,
   anthem, antiphon, antiphony, aria, ballad, benediction, bless,
   bless the Lord, cantata, canticle, carol, celebrate, chant, chirp,
   chirrup, choir, chorale, chorus, church music, cognizance, credit,
   crediting, croon, cry up, descant, ditty, do-re-mi, doxologize,
   doxology, eulogize, exalt, extol, glorify, glorify the Lord,
   gospel, gospel music, grace, hallelujah, hosanna, hum,
   hymn of praise, hymn-tune, hymnody, hymnography, hymnology,
   intonate, intone, introit, laud, lay, lied, lilt, magnify, mantra,
   mass, minstrel, motet, offertory, offertory sentence, oratorio,
   paean, panegyrize, passion, pipe, praise, praise God,
   prayer of thanks, prosodion, psalm, psalmody, quaver, recessional,
   recognition, report, requiem, requiem mass, response, responsory,
   roulade, sacred music, serenade, shake, sing, sing in chorus,
   sing praises, sol-fa, solmizate, spiritual, thank offering,
   thank-you, thanks, thanksgiving, tremolo, trill, troll, tweedle,
   tweedledee, twit, twitter, versicle, vocalize, warble, whistle,
   white spiritual, yodel



Easton's 1897 Bible Dictionary:

Hymn
   occurs only Eph. 5:19 and Col. 3:16. The verb to "sing an hymn"
   occurs Matt. 26:30 and Mark 14:26. The same Greek word is
   rendered to "sing praises" Acts 16:25 (R.V., "sing hymns") and
   Heb. 2:12. The "hymn" which our Lord sang with his disciples at
   the last Supper is generally supposed to have been the latter
   part of the Hallel, comprehending Ps. 113-118. It was thus a
   name given to a number of psalms taken together and forming a
   devotional exercise.

     The noun hymn is used only with reference to the services of
   the Greeks, and was distinguished from the psalm. The Greek
   tunes required Greek hymns. Our information regarding the
   hymnology of the early Christians is very limited.