And for the dictionary, here is another copy & paste job.
spear·head (spîr
h
d
)
n.1. The sharpened head of a spear.
2. a. The leading forces in a military thrust.
b. The driving force in a given action, endeavor, or movement.
tr.v. spear·head·ed,
spear·head·ing,
spear·heads To be the leader of (a movement, for example): "spearheaded the effort to offer classes in settlement houses [and] provide lecturers to women's clubs" (Catherine Clinton).