Done or said with nobody asking, hinting, or reminding. The whole force of the word is in what did NOT happen before it: no question, no nudge, no "go on, say sorry". So it usually carries quiet praise — a child who says thank you unprompted, a colleague who offers help unprompted. That is warmer than it sounds, because we all know how much of our good behaviour comes only after someone pushes. But it can go the other way too: if a person suddenly explains something nobody asked about, "unprompted" hints that this is odd or suspicious — "He told the police, unprompted, that he had never met her." It works both as an adjective before a noun (an unprompted apology) and as a kind of comment dropped into a sentence (she mentioned it, unprompted). In research and surveys it has a technical use: "unprompted awareness" means the brands people name on their own, before you show them a list.

主動的；不用人提醒／不用人開口就做的（自發性的）