Mortal
is,
That which dies.
That which is destined to die.
Though bodies do die, those who are spiritually born again shall be part of the resurrection of the
dead, receiving new, perfect
bodies, which will
never die.
Let not sin therefore reign in your mortal body,
that ye should obey it in the lusts thereof. 
Neither yield ye your members
as instruments of unrighteousness unto sin:
but yield yourselves unto God,
as those that are alive from the dead,
and your members as
instruments of righteousness
unto God.

Romans
6:12-13