guitar (n.) Look up guitar at Dictionary.com
1620s, ultimately from Greek kithara "cithara," a stringed musical instrument related to the lyre, perhaps from Persian sihtar (see sitar); the name reached English several times, including early 14c. giterne, from Old French, in reference to various stringed, guitar-like instruments; the modern word is directly from Spanish guitarra (14c.), which ultimately is from the Greek. The Arabic word is perhaps from Spanish or Greek, though often the relationship is said to be the reverse.