From Longman Dictionary of Contemporary Englishguitargui‧tar /ɡɪˈtɑː $ -ˈtɑːr/ ●●● S3 W3 noun [countable] 
APMa musical instrument usually with six strings that you play by pulling the strings with your fingers or with a plectrum (=small piece of plastic, metal etc)an acoustic/an electric/a classical guitar → bass guitar, steel guitar
APMa musical instrument usually with six strings that you play by pulling the strings with your fingers or with a plectrum (=small piece of plastic, metal etc)an acoustic/an electric/a classical guitar → bass guitar, steel guitarExamples from the Corpus
guitar• Yamaha's factory in Kaohsiung has been building guitars now for over twenty years ... Neville Martenflies East.• He played classical guitar, and our music class was one of the most enjoyable hours for me.• The album is an absolute feast of fully cranked guitar and catchy pop choruses.• The thing it became was an experimental format where Reynolds played guitar, tweaking and warping the sound using effects.• It is a slow, stomping thing with grunting; the guitars hate us and the drums are thick and stupid.• There are no frets or strings on the guitar neck, and thus nothing to do with your left hand.• It's very difficult to describe sounds, but the humbuckers fitted to this guitar exhibit real tone.• Then I saw a gaggle of youths arriving with guitar cases for a recording session, and I changed my mind.Origin guitar (1600-1700) French guitare, from Spanish guitarra, from Arabic qitar, from Greek kithara type of stringed instrument 