spear vs spearhead

spear and spearhead both are nouns.

Word	Noun	Adjective	Verb	Adverb
spear	Yes	No	Yes	No
spearhead	Yes	No	Yes	No

spear (noun)	spearhead (noun)
a long pointed rod used as a tool or weapon	the head and sharpened point of a spear
an implement with a shaft and barbed point used for catching fish	the leading military unit in an attack
	someone who leads or initiates an activity (attack or campaign etc.)

spear (verb)	spearhead (verb)
pierce with a spear	be the leader of
thrust up like a spear