M1p

Make one purlwise is a single stitch increase made on the purl side of row/round. There are multiple ways of making an increase, but generally it means the same as M1lp. This is a finicky stitch and can be a bit tough on your hands.

Insert the left hand needle from front to back into a strand between stitches, insert the right hand needle from left to right into the back loop, purl through.

M1p