rec·tus / ˈrektəs/ • n. (pl. -ti / -tī/ ) Anat. any of several straight structures, in particular: ∎  (also rec·tus ab·dom·i·nis / abˈdämənis/ ) each of a pair of long flat muscles at the front of the abdomen, joining the sternum to the pubis and acting to bend the whole body forward or sideways. ∎  any of a number of muscles controlling the movement of the eyeball.

rectus (rek-tŭs) n. any of several straight muscles. r. abdominis a long flat muscle that extends bilaterally along the entire length of the front of the abdomen. r. femoris see quadriceps. r. muscles of the orbit some of the extrinsic eye muscles.