Box Pleat refers to the style of pleat made of two flat folds turned inwards towards each other, creating a box like shape on the front of the garment.
Other /More definition:
Box Pleat refers to a box shaped pleat with stitches facing the lining. A Box Pleat is a double pleat, with the material folded under at each side. The shirt is described as Box Pleated when two (2) folds of fabric are brought together to form a pleat.

Box Pleat are formed by two folded edges facing each other. Box pleats are evenly spaced and stitched. There are 3 types of Box Pleats:
1. Closed Box Pleats: Pleats of fabric are pressed flat so the edges of the pleats touch each other all the way across the front and all the way across the back of the treatment (three times fullness)
2. Open Box Pleats: Pleats of fabric are taken on the front of the treatment and pressed flat against the front but there is a space between the edges of the peats on the front.
3. Inverted Box Pleats: Pleats of fabric are taken in the back of the treatment and pressed flat against the back but the sides do not touch.

Box Pleat is also called Box Plait. It originated between 1880 to 1885.

Author's Note: I spotted over the internt a 3.1 Phillip Lim
dusky gray cotton trapeze dress with box pleats. I also think that Kilts are usually Box-Pleated

My favorite! A Mike & Chris Graham Box Pleated Jacket which is box-pleated with a tucked bubble hem throughout. Two button closure on front with a stiched collar and cuffs. I found this in http://bigdropnyc.com
List of books: Box,Pleat