Onomatopoeia (on-o-mat-o-pee’-a): Using or inventing a word whose sound imitates that which it names (the union of phonetics and semantics).
My heart went boom, boom, boom. Then it went squish, squish, squish as they gave me CPR. My marathon-running days are over forever! I’ll have to be content with fast walking around the mall or the supermarket.
Definition courtesy of “Silva Rhetoricae” (rhetoric.byu.edu)