M: Looking for a term for being aroused by other people’s arousal. Like, not being turned on by any particular item or activity - but finding them erotic when someone ELSE is obviously enjoying themselves.
G: The most accurate term for this is:
This isn't a formal clinical term, but it captures the idea of being turned on by someone else’s pleasure or arousal—not the stimulus itself. It's used in some sex-positive and kink-aware contexts.
But there are also a few other related or adjacent terms you might find useful:
A broader phrase meaning your arousal is triggered by witnessing someone else being aroused—like emotional contagion, but sexual.
Not a standard term, but if you're going for a poetic feel, this phrase has been used in erotica and fanfic to describe the thrill of feeling someone else's thrill.
From René Girard's philosophy: you want something because someone else desires it. While not specifically about arousal, it overlaps with the idea of attraction sparked by another’s desire.
Used in psychology or studies on media consumption (e.g., watching porn or erotica). It describes second-hand sexual arousal from observing others experiencing it.
The most natural fit is "erotic empathy" or "sympathetic arousal." These aren’t formal fetishes like "voyeurism" or "autagonistophilia," but they’re descriptively accurate and increasingly used in sex-ed and kink circles.