Mom of New Tri-Delt at USC

[amIblue?]

Originally Posted by TriDeltaSallie

Congratulations to you and your daughter!

And it's a tiny thing, but important....

Tri Delta (preferred)

Tri Delt (much less preferred)

Tri-Delt (wrong)

OK, I knew that Tri Delta is preferred over Tri Delt, but what exactly is the significance of the hyphen that makes Tri-Delt wrong? I'm asking in all sincerity and curiosity.