Pronunciation: pro-trak'tor, -tor
A muscle drawing a part forward, as antagonistic to a retractor (the serratus anterior muscle is a protractor of the scapula; the lateral pterygoid muscle is a protractor of the mandible).
[L. pro-traho, pp. -tractus, to draw forth]
Search Stedman's Medical Dictionary
Examples: glitazone, GI cocktail, etc.