Subtriangular :: Subtreasury (n.) A subordinate treasury, or place of deposit; as, the United States subtreasury at New York..
Subtribe :: Subtriangular (a.) Nearly, but not perfectly, triangular..
Subtrihedral :: Subtribe (n.) A division of a tribe; a group of genera of a little lower rank than a tribe.
Subtriple :: Subtrihedral (a.) Approaching the form of a three-sided pyramid; as, the subtrihedral crown of a tooth..