drop anchor vs anchor

drop anchor is not a noun while anchor is a noun.

Word	Noun	Adjective	Verb	Adverb
drop anchor	No	No	Yes	No
anchor	Yes	No	Yes	No

As verbs, drop anchor and anchor are synonyms defined as:

Other synonyms of drop anchor include cast anchor.

drop anchor (noun)	anchor (noun)
	a mechanical device that prevents a vessel from moving
	a central cohesive source of support and stability
	a television reporter who coordinates a broadcast to which several correspondents contribute

drop anchor (verb)	anchor (verb)
secure a vessel with an anchor	secure a vessel with an anchor
	fix firmly and stably