Someone who looks through a small opening or window, especially secretly; also slang for an eye.
From 'peep,' which comes from Middle English and is imitative of the sound a small bird makes, combined with the agent suffix '-er' for 'one who does something.'
Peepers became slang for eyes because when you peek through a hole, you're narrowing your eyes just like when you look intently at something small.
Term carries connotations from historical surveillance norms and gendered violation; 'Peeping Tom' legends and prosecutions asymmetrically targeted voyeurism against women, while the language conflates the act with a masculine character archetype.
Use specific legal/technical term: 'unauthorized surveillance,' 'voyeurism,' or 'privacy violation.' Avoid the diminishing noun form.
["voyeur (if etymology essential)","unauthorized observer","privacy violator"]
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