Noun

• S: (n) spearhead (someone who leads or initiates an activity (attack or campaign etc.))
• S: (n) spearhead (the leading military unit in an attack)
• S: (n) spearhead, spearpoint, spear-point (the head and sharpened point of a spear)

Verb

• S: (v) spearhead (be the leader of) "She spearheaded the effort to find a cure for the disease"