Wythe, as I understand it, is the width of masonry corresponding to one
thickness of a masonry unit.  Hence, a brick bearing wall that is 3
wythes thick has three brick widths plus mortar to equal approximately
13 inches in cross-section.

If I had a construction dictionary at home, I would quote from that, so
this is just a friendly description of how I use the word.

I live on a blvd. or boulevard, but that is entirely different.

Ilene

P.S. I hope this was not a joke, or something, that I missed...