discreetly
In a quiet, careful way so others hardly notice.
To do something discreetly means to do it in a careful, subtle way that doesn't attract attention or cause embarrassment. When you act discreetly, you're being thoughtful about not making a situation awkward or uncomfortable for others.
If you notice a friend has spinach stuck in their teeth during lunch, you might whisper it to them discreetly rather than announcing it loudly to the whole cafeteria. If a teacher wants to help a struggling student without making them feel singled out, she might offer extra help discreetly after class. When you pass a note to a classmate, you do it discreetly so the teacher doesn't see.
The word suggests a combination of tact and awareness. Acting discreetly means understanding that some situations require quiet handling. You're not being secretive in a sneaky way; you're being considerate and wise about how to handle delicate moments.
The opposite would be doing something obviously or conspicuously. If you discreetly check your watch during a boring presentation, you glance quickly without making it obvious. If you do it obviously, you hold your wrist up, stare at it, sigh loudly, and make everyone notice your impatience.