mound vs kopje

mound and kopje both are nouns.

Word	Noun	Adjective	Verb	Adverb
mound	Yes	No	Yes	No
kopje	Yes	No	No	No

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

Other hyponyms of mound include anthill, formicary, koppie, molehill.

mound (noun)	kopje (noun)
the position on a baseball team of the player who throws the ball for a batter to try to hit	a small hill rising up from the African veld
structure consisting of an artificial heap or bank usually of earth or stones
(baseball) the slight elevation on which the pitcher stands
a collection of objects laid on top of each other
a small natural hill

mound (verb)	kopje (verb)
form into a rounded elevation