From Longman Dictionary of Contemporary Englishstrumstrum /strʌm/ verb (strummed, strumming) [intransitive, transitive] APMto play an instrument such as a guitar by moving your fingers up and down across its strings→ See Verb table
Examples from the Corpus
strum• The guitar player strummed along respectfully.• Budd, who has been strumming his acoustic guitar through the Midwest, writes introspective songs with a witty, sincere touch.• Mulcahey strummed his banjo and tapped the castanet again.• One of the minstrels strummed his banjo.• Mike Dawson was sitting at a dead computer, strumming the keyboard and offering a toothy smile to an invisible audience.• When we first started strumming, there was definitely a real affinity with the feel, so who knows?Origin strum (1700-1800) From the sound 