ぜんぜん

ぜんぜん is used to strongly negate or emphasize that something does not happen or is not true. It almost always combines with a negative verb or adjective (e.g., ぜんぜんわかりません, ぜんぜん知らない). In casual speech, ぜんぜん + ない/なかった is common; in formal contexts you’ll hear ぜんぜん…ありません/ありませんでした. It cannot be followed by positive verbs to mean “totally” in standard usage (e.g., ぜんぜんできる is unusual and sounds off; use ぜんぜんできません). The nuance is strong, conveying that something is far from the expected or desired level. Typical contexts include discussions of effort, understanding, performance, or satisfaction.