kid vs stepchild

kid and stepchild both are nouns.

Word	Noun	Adjective	Verb	Adverb
kid	Yes	No	Yes	No
stepchild	Yes	No	No	No

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

Other hyponyms of kid include army brat, babe, baby, infant, female offspring, male offspring, man-child.

kid (noun)	stepchild (noun)
young goat	a child of your spouse by a former marriage
a young person of either sex
a human offspring (son or daughter) of any age
soft smooth leather from the hide of a young goat

kid (verb)	stepchild (verb)
be silly or tease one another
tell false information to for fun