tris-

Etymology
Borrowed from.

Prefix

 * 1)   trisphosphuret of copper is PCu3; trisbenzeneazoresorcinol, C6H(OH)2(N2Ph)3.
 * 2)  A variant of tri-, used for substitutions of three complex rather than simple units, as in,
 * trisbenzene-azophenol, C6H2(N:NC6H5)3OH
 * tristhio-dimethyl-benzaldehyde, {C6H3(CH3)2CHS}3