Nouns

(n)spearheadsomeone who leads or initiates an activity (attack or campaign etc.)
(n)spearheadthe leading military unit in an attack
(n)spearhead, spearpoint, spear-pointthe head and sharpened point of a spear

Verbs

(v)spearheadbe the leader of“She spearheaded the effort to find a cure for the disease”