ἐχθρός
hated, hateful
ἐχθρός hateful (passively, odious, or actively, hostile); usually as a noun, an adversary (especially Satan)
Derivation: from a primary ἔχθω (to hate);
KJV Usage: enemy, foe.
Thayer:
1) hated, odious, hateful
2) hostile, hating, and opposing another
2a) used of men as at enmity with God by their sin
2a1) opposing (God) in the mind
2a2) a man that is hostile
2a3) a certain enemy
2a4) the hostile one
2a5) the devil who is the most bitter enemy of the divine government

ἐχθρός
echthros
ekh-thros'
From a primary word ἔχθω echthō (to hate); hateful (passively odious, or actively hostile); usually as a noun, an adversary (especially Satan)
KJV Usage: enemy, foe.