A gradable adjective is one you can grade: you can put very, fairly, a bit in front of it, or use -er / -est or more / most. Tall, cold, interesting, and expensive are typical. An ungradable (or “absolute”) adjective does not work that way in careful use: atomic, wooden in the “made of wood” sense, married. Teachers use gradable almost only in this grammar sense; outside class, people do not ask “Is this adjective gradable?” They just speak. Though actually, the same spelling can also mean “able to be given a mark or a quality grade” in a school or factory, but here the filing is the language-class meaning. And real speakers stretch the tidy line — very unique is everywhere — so the label describes the usual behaviour of the word, not a law.

（語法）可分級的（形容詞能加 very、比較級）