Longman Dictionary of Contemporary English
stringed instrument
noun
EXAMPLES FROM CORPUS
▪ Flittern Rattletrap hammered the strings of a low-throated stringed instrument, his feet stamping time.
▪ Writing music, the bottom line is that it's a stringed instrument but rhythmically you are playing a keyboard.
Wiktionary
stringed instrument
n. (context music English) Any of very many musical instruments in which taut strings are plucked, bowed or struck in order to produce a sound
WordNet
stringed instrument
n. a musical instrument in which taut strings provide the source of sound