Hi, Gradable adjectives are those that can differ in size, while non-gradable adjectives can't. You may hear the phrase, "it's all relative" (i.e. it all depends on what we are comparing to), and basically gradable adjectives are those that are relative, like hot, tall, heavy, short. Note that extreme adjectives are not gradable adjectives. Gradable adjectives can be used with gradable adverbs. For example, he was slightly rich and very popular. Non-gradable adjectives are those where the word only has one meaning, and it cannot be talked about in a relative sense. So absolute adjectives, extreme adjectives and classifying adjectives are all non-gradable adjectives. Some examples are: Extreme adjective: freezing Absolute adjective: dead, impossible, unique (this is an absolute adjective so it is yes/no, something is either dead or it's not, possible or it's not) Classifying adjective: chemical, digital, domestic With non-gradable adjectives, we typically don't use gradable adverbs. So, for example, we typically don't say "the cat is rather unique" because unique on it's own means one of a kind. Hope this helps!