What is "ketene"

n. 1 (context organic chemistry English) any of a class of unsaturated ketones, having a general formula R₁R₂C=C=O, that react as if they were inner acid anhydrides 2 (context organic compound English) the parent compound of this class, CH₂=C=O, an unstable, reactive colourless gas

A ketene is an organic compound of the form R′R″C=C=O. The term is also used specifically to mean ethenone, the simplest ketene, where R′ and R″ are hydrogen atoms.

Ketenes were first studied as a class by Hermann Staudinger.