in
UK: ɪn | US: ɪn
prep. inside or within a place, container, or area
adv. to or toward the inside
adj. fashionable or trendy (informal)
adj. holding power or influence (e.g., "the in party")
The word "in" traces back to Old English in, derived from Proto-Germanic in, meaning "into" or "inside." It shares roots with Latin in (same meaning) and Greek en. As a core spatial preposition, its simplicity and universality have kept it nearly unchanged across millennia. The informal sense of "fashionable" (e.g., "the in crowd") emerged in the early 20th century, metaphorically extending the idea of being "inside" a privileged group.
She left her keys in the car.
Come in and sit down.
This café is the in place right now.
The tide came in quickly.
He’s been in politics for decades.