mac vs oilskin

mac and oilskin both are nouns.

Word	Noun	Adjective	Verb	Adverb
mac	Yes	No	No	No
oilskin	Yes	No	No	No

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

mac: a waterproof raincoat made of rubberized fabric
oilskin: a macintosh made from cotton fabric treated with oil and pigment to make it waterproof

Other hyponyms of mac include slicker.

mac (noun)	oilskin (noun)
a waterproof raincoat made of rubberized fabric	a macintosh made from cotton fabric treated with oil and pigment to make it waterproof