Murder means "unlawfully taking someone's life." It is true that the death penalty isn't murder, because it's not unlawful. Then again, neither is abortion.
I do not see how a jury deciding on something makes it not murder. If a jury decided to sentence a parking ticket violator to being stoned to death, would that be not murder? That's ridiculous.
Err,
First, criminal homocide, at common law, consists of murder or manslaughter.
Second, a homocide is not criminal if it is: 1) justifiable or 2) excusable.
An example of justifiable homocide is self-defense, while the killing of an enemy combattent is excusable.
Third, abortion is merely lawful because certain members of the judiciary approve of it. It is generally neither justifiable nor excusable.