alkylidene
/alˈkɪlɪdiːn/ /alˈkʌɪlɪdiːn/Chemistry
noun
A compound derived from an alkane by the replacement of two hydrogen atoms on the same carbon atom with one double-bonded atom or group; the divalent functional group =CR′R″ characteristic of such a compound.
Origin
Early 20th century; earliest use found in Journal of Physical Chemistry. From alkyl + -idene.