Source : Webster's Revised Unabridged Dictionary (1913)

Rectus \Rec"tus\ (-t?s), n.; pl. {Recti} (-t?). [NL., fr. L.
   regere to keep straight.] (Anat.)
   A straight muscle; as, the recti of the eye.

Source : WordNet®

rectus
     n : any of various straight muscles
     [also: {recti} (pl)]

recti
     See {rectus}