Instead of a single melody over chords, counterpoint weaves two or more melodies at once. J. S. Bach is its best-known master; his inventions and fugues are built on it.
In a fugue, a short subject is introduced in one voice and imitated by others at different pitches. In modern music, counterpoint appears whenever a bassline, a lead and a countermelody move independently, from film scores to funk.
Using it in a prompt
Ask for "two-part counterpoint" or a "countermelody in the strings" when you want richer, more interwoven arrangements.