A limerick is a humorous poem consisting of five lines. The first, second, and fifth lines must have seven to ten syllables while rhyming and having the same verbal rhythm. The third and fourth lines should only have five to seven syllables; they too must rhyme with each other and have the same rhythm. Here is an example of a limerick:

There once was a man from Nantucket Who kept all his cash in a bucket; But his daughter, named Nan, Ran away with a man, And as for the bucket, Nantucket.

Limericks often start with the line "There once was a..." or "There was a...". They are often funny or nonsensical and can be a great way to introduce children to poetry. Edward Lear, a famous author who wrote the "Book of Nonsense" in the 1800s, made limericks famous.