The trivial name carbene is the preferred IUPAC name. The systematic names methylidene and dihydridocarbon, valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, respectively.
Methylidene is viewed as methane with two hydrogen atoms removed. By default, this name pays no regard to the radicality of the methylene. Although in a context where the radicality is considered, it can also name the non-radical excited state, whereas the radical ground state with two unpaired electrons is named methanediyl.
Methylene is also used as the trivial name for the substituent groups methanediyl (), and methylidene ().
Methylene has an electron affinity of 0.65 eV.