WordNet (r) 3.0 (2006):

onomatopoeical
    adj 1: (of words) formed in imitation of a natural sound;
           "onomatopoeic words are imitative of noises"; "it was
           independently developed in more than one place as an
           onomatopoetic term"- Harry Hoijer [syn: echoic,
           imitative, onomatopoeic, onomatopoeical,
           onomatopoetic] [ant: nonechoic]