serf vs cotter

serf and cotter both are nouns.

Word	Noun	Adjective	Verb	Adverb
serf	Yes	No	No	No
cotter	Yes	No	No	No

As nouns, cotter is a hyponym of serf; that is, cotter is a word with a more specific, narrower meaning than serf:

serf: (Middle Ages) a person who is bound to the land and owned by the feudal lord
cotter: a medieval English villein

Other hyponyms of serf include cottier.

serf (noun)	cotter (noun)
(Middle Ages) a person who is bound to the land and owned by the feudal lord	fastener consisting of a wedge or pin inserted through a slot to hold two other pieces together
	a medieval English villein
	a peasant farmer in the Scottish Highlands