Tri- (?). [Gr. tri- or L. tri-, sometimes through French; akin to L. tres three, and E. three. See Three.]
A prefix meaning three, thrice, threefold; as in tricolored, tridentate.
A prefix (also used adjectively) denoting three proportional or combining part, or the third degree of that to the name of which it is prefixed; as in trisulphide, trioxide, trichloride.
© Webster 1913.