A homing missile was a special type of missile. The term was used to generally describe many types of weapons, including brilliant missiles and many types of concussion missiles, as it simply designated a guided missile.
Card Text/Abilities
ATTACK (TARGET LOCK): Discard this card to perform this attack.
The defender cannot spend evade tokens during this attack.
FAQ
The attacker must have a target lock on the defender to use Homing Missiles, but the target lock is not spent in order to perform the attack. (X-Wing FAQ, Version 3.1.1, Updated 07/24/2015)