The word 'whimper' is believed to be onomatopoeic in origin, first appearing in English in the early 16th century. It was formed to imitate the sound of feeble, intermittent crying or complaining. This places it in a category with other expressive verbs like 'whine' and 'murmur,' which also echo the noises they represent. The word's journey is not one of classical roots combining, but rather a direct phonetic imitation that became lexicalized, capturing a specific, plaintive vocal quality in a stable form.

The word 'whimper' is a simplex word, likely of imitative origin, formed to mimic the sound it describes. Its functional role is as a complete lexical unit.