also: ましん
Refers to a malevolent supernatural being, often with great power. Can be used in fantasy, mythology, or metaphorically for a cruel person.
その魔神は村を破壊した。
The demon destroyed the village.
There's a legend that a devil appeared at the old temple.
彼はまるで魔神のように冷酷だ。
He is as ruthless as a devil.
The hero defeated the devil to protect the village.
鬼 is the classic Japanese ogre/demon with horns and a fierce look, whereas 魔神 is a broader term for any powerful evil spirit or god.
妖怪 covers a wide range of supernatural creatures, not necessarily evil, while 魔神 specifically implies malevolence and great power.
天使 is a benevolent, protective being, the mythological opposite of the malevolent 魔神.
Standard kanji spelling. The reading まじん is the most common.
Alternate reading, less common but still encountered.
Compound of 魔 (ma, 'demon, evil influence') and 神 (shin/jin, 'god, deity'). The combination suggests a god-like being of evil nature.