tarn vs lake

tarn and lake both are nouns.

Word	Noun	Adjective	Verb	Adverb
tarn	Yes	No	No	No
lake	Yes	No	No	No

As nouns, lake is a hypernym of tarn; that is, lake is a word with a broader meaning than tarn:

tarn (noun)	lake (noun)
a mountain lake (especially one formed by glaciers)	a body of (usually fresh) water surrounded by land
	any of numerous bright translucent organic pigments
	a purplish red pigment prepared from lac or cochineal