- The sharpened head of a spear. (noun)
- The leading forces in a military thrust. (noun)
- The driving force in a given action, endeavor, or movement. (noun)
- 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). (verb-transitive)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.