monomethyl
/ˌmɒnə(ʊ)ˈmiːθʌɪl/ /ˌmɒnə(ʊ)ˈmɛθʌɪl/ /ˌmɒnə(ʊ)ˈmɛθ(ɪ)l/Chemistry
adjective
Attributive Designating an organic compound in which a methyl radical takes the place of one hydrogen atom.
Origin
Mid 19th century. From mono- + methyl. Compare earlier trimethyl.