To open a buckle — the metal fastener on a belt, a shoe strap, a watch band, a schoolbag, or a seatbelt. You unbuckle a thing by pushing or pulling the metal tongue out of its hole so the two ends come apart. It is a small, plain, physical word: you do it with your hands, and you can hear the click. Note what it takes as its object. You unbuckle the belt, or the shoe, or the seatbelt — the thing that is fastened. In careful English you also unbuckle the buckle itself, but that sounds a little odd to most ears; people name the bigger thing. There is one common extension beyond real buckles: on a plane, the announcement is about the seatbelt sign, and people say "you can unbuckle now" with no object at all, just meaning "you may release your seatbelt." Beyond that, this word stays literal. Unlike some un- verbs, it has not grown a figurative life — you do not unbuckle your feelings or unbuckle a problem. If nothing is fastened with an actual buckle, this is the wrong word: clothes with buttons get unbuttoned, a zip gets unzipped, laces get untied.

解開（皮帶、鞋子、安全帶的）扣環。注意：中文常說「解開安全帶」，但英文 unbuckle 只用在有金屬扣環的東西上；沒有扣環的就不能用。