It's technically "homocide." "Murder" is a legal term and is defined by the laws. Generally it means the unjustified killing of another. Dictionary.com says "an unlawful killing." Self-defense is a legitimate justification.
Homocide is not always wrong. Murder is.
In the case of abortion, there is the added argument of whether or not a fetus is a human being.
That's a losing argument. I am more respectful of those who acknowledge that it is a human life, but that it enjoys fewer protections than a more-developed life.
SD
A fair point. However, my argument remains the same: we have decided to exclude certain things, such as abortion and self-defense, from the definition of "murder."