The name travels from Greek kithara through Arabic qītār, Spanish guitarra and French guitare before reaching English.
This is the history of the name. It does not mean the ancient instrument was identical to a modern guitar.
Sources
- Merriam-Webster: guitar
Word History gives all five stages; Kids Definition supports the modern instrument description.
- Online Etymology Dictionary · guitar
Meanings of the older forms on the word path.
- logeion.uchicago.edu · κιθάρα
Meanings of the older forms on the word path.