n. Any of several straight muscles in various parts of the body, as of the abdomen, thigh, eye etc.
the GNU version of the Collaborative International Dictionary of English
n. A straight muscle.
The Century Dictionary and Cyclopedia
n. In anatomy, one of several muscles so called from the straightness of their course, either in their own axis or in the axis of the body or part where they lie.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. any of various straight muscles
Word Usage
"Thus, if the internal rectus is shortened, the eye turns in; if the external rectus, the eye turns out, producing what is known as "wall eye.""