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