• (n.) That which ruffles; specifically, a sewing machine attachment for making ruffles. • (n.) One who ruffles; a swaggerer; a bully; a ruffian.
Ruf'fler noun 1. One who ruffles; a swaggerer; a bully; a ruffian. « Assaults, if not murders, done at his own doors by that crew of rufflers .» Milton. 2. That which ruffles; specifically, a sewing machine attachment for making ruffles. 
This is a sewing machine attachment used to make ruffles.
An attachment to your sewing machine that you fit instead of a foot. It can be used to gather/pleat the fabric as you sew. It differs from a small gathering foot as the gathers can be adjusted in length and frequency of tucks.