Offences Against the Human Body
Causing death by an act done with intention to cause death, or intention to cause bodily injury likely to cause death, or with knowledge that the act is likely to cause death, is "culpable homicide". Causing bodily injury that accelerates the death of someone already suffering a disorder/disease counts as causing their death; death caused despite the possibility of prevention through proper treatment still counts; causing an unborn child's death isn't homicide, but causing the death of a child partially born (even if not breathing) can be.
This defines the general category of unlawfully causing someone's death - "culpable homicide" is the broader umbrella term, with "murder" (Section 101) being a more serious specific subset of it based on the offender's precise intent and circumstances.
This is the foundational definition underlying all of India's homicide law - understanding whether a death-causing act meets this definition is the first step before determining whether it rises to the more serious offence of murder.