1.  limerick(n = noun.location) - port city in southwestern Ireland;
is a kind of city, metropolis, urban center, port
is a part of eire, ireland, irish republic, republic of ireland

2.  limerick(n = noun.communication) - a humorous verse form of 5 anapestic lines with a rhyme scheme aabba;
is a kind of rhyme, verse

   A humorous, often nonsensical, and sometimes risqé poem of five anapestic lines, of which lines 1, 2, and 5 are of three feet, and rhyme, and lines 3 and 4 are of two feet, and rhyme.
"There was a young lady, Amanda,
Whose Ballades Lyriques were quite fin de
Si, I deem
But her Journal Intime
Was what sent her papa to Uganda." [Webster 1913 Suppl.]

limerick, n. a humorous or comic form of five-line stanza with a rhyme-scheme aabba.

Etymology:
said to be from the chorus 'will you come up to Limerick?' sung between improvised verses at a gathering: f. Limerick in Ireland