(intransitive) To move gently and vertically, in either a single motion or repeatedly up and down, at or near the surface of a body of water, or similar medium.

A bobbing motion; a quick up and down movement. / A curtsy. / A bobber (buoyant fishing device). / Any of various hesperiid butterflies.

A bob haircut. / Any round object attached loosely to a flexible line, a rod, a body part etc., so that it may swing when hanging from it. / The dangling mass of a pendulum or plumb line.

(transitive) To cut (hair) into a bob haircut. / (transitive) To shorten by cutting; to dock; to crop. / To bobsleigh.

(Kenya, slang; UK and Australia, historical, dated) A shilling. / (Australia, dated slang) A 10-cent coin. / (slang) An unspecified amount of money.

Abbreviation of shishkabob.

(computer graphics, demoscene) A graphical element, resembling a hardware sprite, that can be blitted around the screen in large numbers.

(humorous) Vibrator (device designed to stimulate a woman's genitals).

(philately) Back-of-the-book; denoting those stamps in a catalogue that are not used for the payment of regular postage fees, and are displayed separately in the catalogue after that listing; the division between these two groups varies with the publisher.

A diminutive of the male given name Robert. / (cryptography, physics) The person or system receiving a message or signal from a source conventionally known as Alice.