Meanings of trigonal in English

Boron atoms are found in trigonal prisms formed by metal atoms.

Lithium ions intercalate into a WO 3 crystal framework and occupy trigonal cavity sites during the electrochemical polarization.

The trigonal crystal forms contain one virion per unit cell and the orthorhombic form contains two particles per cell.

The difference between the two trigonal crystal forms is 1.1 degrees in the orientation of the virus particle as determined from the rotation function.