Casual acquaintances are people you know but aren't close friends with. You recognize them and may chat briefly, but the relationship stays superficial and limited to certain situations. It's more than a stranger, but clearly less close than a friend.

Casual acquaintances are people you are familiar with by name, face, or role, but with whom you do not share personal details or strong emotional bonds. Interactions are usually polite and friendly but occasional and brief, often tied to a place or activity (work, school, or the neighborhood).

For example:

Most of my coworkers are casual acquaintances, but only two of them are close friends.

Maria is just a casual acquaintance from my yoga class; we chat before it starts, but we’ve never met outside the studio.

I wouldn’t share something that personal with a casual acquaintance.