The word 'strum' is a classic example of onomatopoeia, a linguistic process where a word's sound imitates the natural sound associated with the action or thing it describes. First appearing in English in the late 18th century, it was likely coined to mimic the rhythmic, often non-melodic, sound produced by casually brushing the strings of an instrument like a guitar or banjo. This imitative origin bypasses the need for a complex etymology from Latin or Greek, as the word's form is directly and intuitively linked to its auditory essence. Its subsequent development into both a verb and a noun follows a common pattern for such sound-symbolic words in English.

The word is an onomatopoeic formation, imitating the sound of fingers brushing across strings. It is not productively built from classical roots in its modern English form.