Subsesqui-

Sub`ses´qui-


1.(Chem.) A prefix (also used adjectively) denoting the combination of constituents (especially electro-negative and electro-positive bodies) in the proportion of two to three; as, a subsesqui acetate, i. e., a salt having two equivalents of acetic acid to three of the base.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.