Giving false evidence under oath is defined under section -

Sec 191 IPC states that whoever, being legally bound by an oath or by an express provision of law to state the truth, or being bound by law to make a declaration upon any subject, makes any statement which is false, and which he either knows or believes to be false or does not believe to be true, is said to give false evidence. Dr. K. S. Narayan Reddys Synopsis of Forensic Medicine & Toxicology 27th edition pg. 7.