Definify.com
Webster 1913 Edition
Tri-
Tri-
.1.
A prefix meaning three, thrice, threefold; as in
tri
colored, tri
dentate. 2.
(Chem.)
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
tri
sulphide, tri
oxide, tri
chloride.