pls explain frats that arent greek letters

There are three fraternities in the NIC (National Interfraternity Council) that don't have Greek letters: Acacia, Farmhouse & Triangle.

Acacia is a Greek word, Farmhouse was founded by a bunch of farmers and Triangle was founded by architects and engineers. The founders of the three wanted to choose words that stood out from the rest and reflect ideals for their organizations instead of two or three letters.