When a poet writes an emotional, rhyming poem, she can call it a lyric poem.
Lyric poems have a musical rhythm, and their topics often explore romantic feelings or other strong emotions. You can usually identify a lyric poem by its musicality: if you can imagine singing it, it's probably lyric. In ancient Greece and Rome, lyric poems were in fact sung to the strums of an accompanying lyre. It's the word lyre, in fact, that is at the root of lyric; the Greek lyrikos means "singing to the lyre."
Hamlet killed Polonius on accident, realizing that someone was listening to his conversation with his mother in a deranged state. This proves Hamlet to be "crazy", and turns Hamlet into a more disliked person among the kingdom.
