the word 'spearhead' is a transparent compound from old english, formed from 'spere' (spear) and 'heafod' (head). its literal meaning, the pointed tip of a spear, is a direct combination of its parts. this concrete meaning evolved metaphorically to denote the leading element of an advancing force or movement, as the spearhead is the first part to make contact. the verb sense, meaning to lead such an advance, developed naturally from this noun in the early 20th century.

Structure: spear + head spear (old english, a weapon with a long shaft and a sharp point) + head (old english, the top or front part of something)