The Collaborative International Dictionary of English v.0.48:

Rhyme \Rhyme\, n. [OE. ryme, rime, AS. r[imac]m number; akin to
   OHG. r[imac]m number, succession, series, G. reim rhyme. The
   modern sense is due to the influence of F. rime, which is of
   German origin, and originally the same word.] [The Old
   English spelling rime is becoming again common. See Note
   under Prime.]
   1. An expression of thought in numbers, measure, or verse; a
      composition in verse; a rhymed tale; poetry; harmony of
      language. "Railing rhymes." --Daniel.
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            A ryme I learned long ago.            --Chaucer.
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            He knew
            Himself to sing, and build the lofty rime. --Milton.
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   2. (Pros.) Correspondence of sound in the terminating words
      or syllables of two or more verses, one succeeding another
      immediately or at no great distance. The words or
      syllables so used must not begin with the same consonant,
      or if one begins with a vowel the other must begin with a
      consonant. The vowel sounds and accents must be the same,
      as also the sounds of the final consonants if there be
      any.
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            For rhyme with reason may dispense,
            And sound has right to govern sense.  --Prior.
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   3. Verses, usually two, having this correspondence with each
      other; a couplet; a poem containing rhymes.
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   4. A word answering in sound to another word.
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   Female rhyme. See under Female.

   Male rhyme. See under Male.

   Rhyme or reason, sound or sense.

   Rhyme royal (Pros.), a stanza of seven decasyllabic verses,
      of which the first and third, the second, fourth, and
      fifth, and the sixth and seventh rhyme.
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WordNet (r) 3.0 (2006):

rhyme royal
    n 1: a stanza form having seven lines of iambic pentameter;
         introduced by Chaucer