ˈ ̷ ̷ ̷ ̷ˌtil noun
( -s )
Etymology: Greek mesitēs mediator + English -yl
1. : a hypothetical radical C 3 H 5 of which mesityl oxide was once regarded as the oxide and acetone as the hydroxide
2. : either of two univalent radicals C 9 H 11 derived from mesitylene by removal of one hydrogen atom:
a. : the substituted phenyl radical (CH 3 ) 3 C 6 H 2 −
b. : the substituted benzyl radical (CH 3 ) 2 C 6 H 3 CH 2 −; 3,5-dimethyl-benzyl — called also alpha-mesityl