Methionic
Meth`i`on´ic
a. 1. (Chem.) Of, pertaining to, or designating, a sulphonic (thionic) acid derivative of methane, obtained as a stable white crystalline substance, CH2.(SO3H)2, which forms well defined salts.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.