baby vs undertaking

baby and undertaking both are nouns.

Word	Noun	Adjective	Verb	Adverb
baby	Yes	No	Yes	No
undertaking	Yes	No	No	No

As nouns, undertaking is a hypernym of baby; that is, undertaking is a word with a broader meaning than baby:

Other hypernyms of baby include labor, labour, project, task.

baby (noun)	undertaking (noun)
a project of personal concern to someone	any piece of work that is undertaken or attempted
a very young mammal	the trade of a funeral director
a very young child (birth to 1 year) who has not yet begun to walk or talk
the youngest member of a group (not necessarily young)
an immature childish person
an unborn child; a human fetus
a beloved person; used as terms of endearment

baby (verb)	undertaking (verb)
treat with excessive indulgence