What do you call this relationship?

In filling out the details of the family tree of one of my cousins I came across this history: My aunt married a man whose parents, Al and Theresa, both have the same great-grandmother but two different great-grandfathers. In other words, the great-grandmother married and had a child, and then her husband died and she remarried and had another child. Al is a descendant from the first marriage and Theresa from the second.

Is there a name for Al and Theresa's relationship to each other (besides husband and wife, obviously)

They are 2nd half-cousins, I think.

Okay, that sounds sensible. I'll go with that.

Many of the genealogy software companies offer built-in relationship calculators. I often "cheat" and use them!