The Japanese adverb '全然 (ぜんぜん)' is commonly used to express 'not at all' or 'entirely not'. It is often used in negative sentences to emphasize the complete absence or negation of something. For example: I don't understand at all「全然わからない」(ぜんぜんわからない). This is not interesting at all「これは全然面白くない」(これはぜんぜんおもしろくない). It can also be used in casual speech to mean 'completely' or 'totally' in positive contexts, though this usage is more informal. For example: I'm completely fine「全然平気だよ」(ぜんぜんへいきだよ).