foot vs in

foot and in both are nouns.

Word	Noun	Adjective	Verb	Adverb
foot	Yes	No	Yes	No
in	Yes	Yes	No	Yes

foot (noun)	in (noun)
travel by walking	a unit of length equal to one twelfth of a foot
any of various organs of locomotion or attachment in invertebrates
the pedal extremity of vertebrates other than human beings
lowest support of a structure
a support resembling a pedal extremity
the part of the leg of a human being below the ankle joint
(prosody) a group of 2 or 3 syllables forming the basic unit of poetic rhythm
an army unit consisting of soldiers who fight on foot
the lower part of anything
a member of a surveillance team who works on foot or rides as a passenger
a linear unit of length equal to 12 inches or a third of a yard

foot (adverb)	in (adverb)
	to or toward the inside of