rainure d'aiguille

CONT: On the front of the [machine] needle, you'll see the point of the needle that pierces the fabric. Above that is the eye which the top thread runs through, and the groove which runs all along the shaft of the needle. This groove allows the thread to be nestled inside, protecting it as the needle runs through the material and keeping it out of the way so it can glide through the material without protruding, thus creating smooth and even stitches.