spyhole vs peephole

spyhole and peephole both are nouns.

Word	Noun	Adjective	Verb	Adverb
spyhole	Yes	No	No	No
peephole	Yes	No	No	No

As nouns, spyhole and peephole are synonyms defined as:

spyhole and peephole: a hole (in a door or an oven etc) through which you can peep

Other synonyms of spyhole include eyehole.

spyhole (noun)	peephole (noun)
a hole (in a door or an oven etc) through which you can peep	a hole (in a door or an oven etc) through which you can peep