What is adjacent?

Adjacent means no greater than 1 space away. Any object 0 or 1 space away from your current location is adjacent to you.

Dog Fight: Starship Edition FAQ what is adjacent

Some cards specify an adjacent target. They may also state the adjacent target must be in range. If the target is not visible (such as with the STEALTH ability) it is not automatically "in range". Read card text carefully.

The armor card "Reactive Armor: Electromagnetic" does not designate a "target" but it does inflict effect damage to an adjacent attacking vessel.