Source : Webster's Revised Unabridged Dictionary (1913)

Sonnet \Son"net\, v. i.
   To compose sonnets. ``Strains that come almost to
   sonneting.'' --Milton.

Sonnet \Son"net\, n. [F., fr. It. sonetto, fr. suono a sound, a
   song, fr. L. sonus a sound. See {Sound} noise.]
   1. A short poem, -- usually amatory. [Obs.] --Shak.

            He had a wonderful desire to chant a sonnet or hymn
            unto Apollo Pythius.                  --Holland.

   2. A poem of fourteen lines, -- two stanzas, called the
      octave, being of four verses each, and two stanzas, called
      the sestet, of three verses each, the rhymes being
      adjusted by a particular rule.

   Note: In the proper sonnet each line has five accents, and
         the octave has but two rhymes, the second, third,
         sixth, and seventh lines being of one thyme, and the
         first, fourth, fifth, and eighth being of another. In
         the sestet there are sometimes two and sometimes three
         rhymes; but in some way its two stazas rhyme together.
         Often the three lines of the first stanza rhyme
         severally with the three lines of the second. In
         Shakespeare's sonnets, the first twelve lines rhymed
         alternately, and the last two rhyme together.

Source : WordNet®

sonnet
     n : a verse form consisting of 14 lines with a fixed rhyme
         scheme
     v 1: praise in a sonnet
     2: compose a sonnet