search vs horn in

search is a noun but horn in is not a noun.

Word	Noun	Adjective	Verb	Adverb
search	Yes	No	Yes	No
horn in	No	No	Yes	No

As verbs, horn in is a hyponym of search; that is, horn in is a word with a more specific, narrower meaning than search:

Other hyponyms of search include hunt, cruise, prospect, intrude, nose, poke, pry.

search (noun)	horn in (noun)
the activity of looking thoroughly in order to find something or someone
boarding and inspecting a ship on the high seas
an investigation seeking answers
the examination of alternative hypotheses
an operation that determines whether one or more of a set of items has a specified property

search (verb)	horn in (verb)
inquire into	search or inquire in a meddlesome way
try to locate or discover, or try to establish the existence of
subject to a search
search or seek