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.
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         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.
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   Hymn book, a book containing a collection of hymns, as for
      use in churches; a hymnal.
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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.
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         To hymn the bright of the Lord.          --Keble.
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         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.
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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"