The Collaborative International Dictionary of English v.0.48:

Recti- \Rec"ti-\ (r?k"t?*). [L. rectus straight.]
   A combining form signifying straight; as, rectilineal, having
   straight lines; rectinerved.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]