an eyed stitch-forming element which carries an under thread or a cover thread on some types of sewing machine
or cankerworm or inchworm Larva of any member of a large, widespread group (mostly in the family Geometridae, with some in the family Noctuidae) of moths. Loopers move in a characteristic "inching" or "looping" gait by extending the front part of the body and bringing the rear up to meet it. Resembling twigs or leaf stems, they feed on foliage, and can seriously damage or destroy trees
Noun: It's the thingie in the serger that carries the threads that form the overlock part of the serger stitch Usually there are two, upper and lower There may be a third which forms the lower part of the chain stitch