Where did the term “knockers” originate, concerning a womans breasts?
The door-knocker meaning was explained in terms of metonymy (the object used to knock is named after the person who is doing the knocking). As for the breast meaning, a wealth of links were offered: metaphorical links to the door-knocker meaning – breasts resemble some door knockers – breasts protrude like door knockers a metonymical link to the door-knocker meaning – breasts are something one grabs (or feels like grabbing) like a door-knocker metaphorical links to senses of to knock – the sexual impact of breasts may knock you over – when women run, breasts may move up and down, which resembles the act of knocking on doors – breasts knock together Thus the linear theory fails on two counts: i) there is no definite way of deciding which is the literal meaning; and ii), the link between literal and derived meanings cannot always be specified with certainty, even when it is established.
