cithern vs cither

cithern and cither both are nouns.

Word	Noun	Adjective	Verb	Adverb
cithern	Yes	No	No	No
cither	Yes	No	No	No

As nouns, cithern and cither are synonyms defined as:

cithern and cither: a 16th century musical instrument resembling a guitar with a pear-shaped soundbox and wire strings

Other synonyms of cithern include citole, cittern, gittern.

cithern (noun)	cither (noun)
a 16th century musical instrument resembling a guitar with a pear-shaped soundbox and wire strings	a musical stringed instrument with strings stretched over a flat sounding board; it is laid flat and played with a plectrum and with fingers
	a 16th century musical instrument resembling a guitar with a pear-shaped soundbox and wire strings