According to S.375, I.P.C., all of the following are considered as rape, EXCEPT:
Wife of another person
Own wife below 15 years
Age below 16 years of age
Against wife's consent
Sexual intercourse by a man with his own wife (even against her will) is not rape, if she is above 15 years of age. A man is said to commit rape, if he has sexual intercourse with a woman with or without her consent, when she is under 16 years of age. Ref: The Essentials of Forensic Medicine and Toxicology by Dr K. S.Narayan Reddy, 27th edition, Page 351.