knock [OE] The origin of this word is probably an attempt to imitate the sound. When you decide to finish an idea or plan you may say that you are going to knock it on the head, a phrase well established in English by the late 16th century. To knock spots off [M19th] someone is to outdo them easily and probably comes from the beating sense of knock, also found in to knock someone’s head off [M19th], knock into next week [E19th], and originally in knock into a cocked hat [M19th], which could mean ‘to damage someone or something beyond recognition’ as well as the modern metaphorical sense. The sense ‘speak disparagingly about’ is recorded from the late 19th century in US usage. Knocked up, ‘pregnant’, is early 19th century.