Real Dictionary

slip stitch in American English
a continuous stitch, especially for a hem, in which the needle is put through the folded part of the hem, picking up a few threads of the fabric on the inside, so as to be invisible on the outside
noun: a loose stitch taken between two layers of fabric, as on a facing or hem, so as to be invisible on the right side or outside surface, used in stoating

slip stitch in British English
noun: a sewing stitch for securing hems, etc, in which only two or three threads of the material are caught up by the needle each time, so that the stitches are nearly invisible from the right side

slip-stitch in American English
to sew with slip stitches

slip-stitch in British English
verb: to join two edges using slip stitches