Greek 'phobos' originally meant 'flight' — fear was the impulse to run before it became the emotion itself.
An extreme or irrational fear or aversion to something; in psychiatry, an anxiety disorder defined by persistent and excessive fear of a specific object, situation, or activity.
From Greek 'phóbos' (fear, panic, flight from fear), often personified as Phobos, the god of fear and son of Ares, god of war. The Greek 'phóbos' derives from PIE *bʰegʷ- (to run, to flee), reflecting an original meaning of 'flight' that shifted to 'fear' — the emotion that causes flight. The word entered English as a standalone noun in the late eighteenth century, extracted from the many compound terms ending
The Mars moon Phobos is named after the Greek god of fear, son of Ares (Mars). Its companion moon is Deimos, named for the god of terror. The two tiny moons were discovered by Asaph Hall in 1877, who named them for the personified attendants of the war god — fear and terror riding alongside battle, just as the moons ride alongside Mars.