knee-highTranslate knee-high | into German | into Spanish Definition of knee-high adjective & adverb so high as to reach the knees: [as adjective]:knee-high boots [as adverb]:they were wading knee-high in the water noun (usually knee-highs) a nylon stocking with an elasticated top that reaches to a person’s knee. Phrases knee-high to a grasshopper informal very small or very young. knee-high in other Oxford dictionaries Definition of knee-high in the US English dictionary