noun
demon; devil; evil spirit; evil influence
Refers to supernatural evil beings or a malign force. Often used in compounds and set phrases.
彼はまるで魔が差したかのように嘘をついた。
He told a lie as if possessed by an evil spirit.
魔を払うお守りを買った。
I bought a charm to ward off evil spirits.
noun, used as a suffix
-crazed person; -obsessed person; fiend
Suffix attached to nouns to describe someone obsessed with or addicted to that thing. Common in words like 覗き魔 (voyeur) or 仕事の魔 (workaholic).
See also: 覗き魔
彼は本当に仕事の魔だ。
He is a real workaholic.
覗き魔に注意してください。
Beware of peeping toms.
noun which may take the genitive case particle 'no'
dreaded; terrible; awful; dreadful
Used as a no-adjective to describe something fearsome or extremely bad. Often appears in fixed expressions like 魔の海域 (treacherous waters) or 魔の時間 (dreaded hour).
魔の海域と呼ばれる場所がある。
There is a place called the treacherous waters.
魔の時間帯に外出するのは避けている。
I avoid going out during the dreaded hours.
悪魔 specifically means 'devil' or 'demon' as a concrete entity, while 魔 can be a broader concept of evil influence or a suffix.
鬼 is an ogre or demon from Japanese folklore, often depicted as a horned monster, whereas 魔 is a more abstract evil spirit or influence.
The kanji 魔 is a phono-semantic compound, with 鬼 (demon) as the semantic component and 麻 (hemp) as the phonetic. The reading ま is the on'yomi. The word has been used in Japanese for centuries to refer to evil spirits and influences, and later extended to obsessive behavior.