the compound word 'thigh-high' is a modern english formation that transparently combines two native germanic elements. the first element, 'thigh', has maintained a remarkably stable meaning from its old english form 'þēoh', referring specifically to the upper leg. the second element, 'high', from old english 'hēah', broadly denotes elevation or great vertical extent. when combined, the compound creates a descriptive term whose literal meaning, "as high as the thigh," directly informs its modern application to garments like socks or boots. this logical construction follows a common english pattern for specifying the length or coverage of clothing items, such as 'knee-high' or 'ankle-high'.

Structure: thigh (body part) + high (elevated position) thigh: from old english 'þēoh', of germanic origin, related to dutch 'dij' and german 'dich'. it denotes the part of the leg between the hip and the knee. high: from old english 'hēah', of germanic origin, related to dutch 'hoog' and german 'hoch'. it indicates a great vertical extent or an elevated position.