hammock vs kopje

hammock and kopje both are nouns.

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

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

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

hammock (noun)	kopje (noun)
a hanging bed of canvas or rope netting (usually suspended between two trees); swings easily	a small hill rising up from the African veld
a small natural hill