Someone who is indiscreet is careless about what they say or do, especially by talking about things that should stay private. An indiscreet remark lets a secret out. An indiscreet question in a crowded room can make someone go red. It is about poor judgment and loose talk, not always about wanting to hurt people — though it can hurt them all the same. It is a fairly formal, slightly old-fashioned criticising word. In casual talk people more often say “you shouldn't have said that” or “that was too much information.” Though actually, what counts as indiscreet changes with the room: a joke that is fine among close friends can be indiscreet at work.