oiler vs wildcat well

oiler and wildcat well both are nouns.

Word	Noun	Adjective	Verb	Adverb
oiler	Yes	No	No	No
wildcat well	Yes	No	No	No

As nouns, wildcat well is a hyponym of oiler; that is, wildcat well is a word with a more specific, narrower meaning than oiler:

oiler: a well that yields or has yielded oil
wildcat well: an exploratory oil well drilled in land not known to be an oil field

Other hyponyms of oiler include gusher, spouter, stripper, stripper well, wildcat.

oiler (noun)	wildcat well (noun)
a cargo ship designed to carry crude oil in bulk	an exploratory oil well drilled in land not known to be an oil field
a well that yields or has yielded oil
a worker who oils engines or machinery