peeping Tom; voyeur
Refers to a person who secretly watches others, especially for sexual gratification. Often used in criminal or creepy contexts.
Apparently a peeping Tom has been spotted in the neighboring apartment building.
The police arrested the voyeur.
Standard kanji spelling.
Mixed kana-kanji spelling, sometimes used for clarity or in less formal contexts.
Compound of 覗き (のぞき, 'peeping', from 覗く) and 魔 (ま, 'demon' or 'fiend'), literally 'peeping fiend'.