cotter pin vs cottar

cotter pin and cottar both are nouns.

Word	Noun	Adjective	Verb	Adverb
cotter pin	Yes	No	No	No
cottar	Yes	No	No	No

As nouns, cottar is a hypernym of cotter pin; that is, cottar is a word with a broader meaning than cotter pin:

cotter pin: a cotter consisting of a split pin that is secured (after passing through a hole) by splitting the ends apart
cottar: fastener consisting of a wedge or pin inserted through a slot to hold two other pieces together

Other hypernyms of cotter pin include cotter.

cotter pin (noun)	cottar (noun)
a cotter consisting of a split pin that is secured (after passing through a hole) by splitting the ends apart	fastener consisting of a wedge or pin inserted through a slot to hold two other pieces together
	a peasant farmer in the Scottish Highlands