ˈkēˌtēn noun
( -s )
Etymology: International Scientific Vocabulary ket- + -ene; originally formed as German keten
: a colorless poisonous gaseous compound CH 2 . C . O of penetrating odor that is made by pyrolysis of acetic acid or acetone and used as an acetylating agent (as in making acetic anhydride from acetic acid or acetic esters from alcohols) ; also : any of various derivatives of this compound — see diketene