ETYM French, from Italian sonetto, from suono a sound, a song, from Latin sonus a sound. Related to Sound noise.
A verse form consisting of 14 lines with a fixed rhyme scheme.
Fourteen-line poem of Italian origin introduced to England by Thomas Wyatt in the form used by Petrarch (rhyming abba abba cdcdcd or cdecde) and followed by Milton and Wordsworth; Shakespeare used the form abab cdcd efef gg.
In the final couplet Shakespeare summed up the argument of the sonnet or introduced a new, perhaps contradictory, idea. The difference in the rhyme scheme of the first eight lines (the octet) and the last six (the sestet) reflected a change in mood or direction of the Petrarchan sonnet.

1. To compose a sonnet.
2. To praise in a sonnet.