also: オノマトペー
onomatopoeia
Linguistic term for words that phonetically imitate sounds, such as animal noises or environmental sounds. In Japanese, often used alongside 擬音語 (giongo) and 擬態語 (gitaigo).
from French onomatopée
Japanese has many onomatopoeic words.
"Wan-wan" is an onomatopoeia for a dog's bark.