The nature and source of onomatopeic words in Spanish are discussed in order of decreasing resemblance to the sound imitated. The first group of onomatopeic words are the interjections, in which sound effects and animal sounds are expressed. Repetition is often used to enhance the effect. The second group includes verbs and nouns derived from the interjections. In Spanish most such verbs belong to the first conjugation, e.g. "aullar,""balar,""bramar,""ladrar"; however, their respective noun forms, "aullido,""balido,""bramido,""ladrido," resemble phonetic participles of the second and third conjugation. A third group consists of words formed from a root plus the suffix -azo. The root corresponds to the name of the object or instrument which will affect the action. The suffix"-azo" gives force to this object or instrument. The phonological source of the noun suffix is assumed to be the Latin adjective suffix "-aceu," which indicates resemblance, composition, or the material of which meaning is made. However, its development meaning as a noun suffix is a Spanish innovation that is better understood in the context of onomatopeia. (LMO)