From Longman Dictionary of Contemporary Englishcurlercurl‧er /ˈkɜːlə $ ˈkɜːrlər/ noun [countable] 
DCa small plastic or metal tube used for making hair curl SYN roller Her hair was in curlers.
DCa small plastic or metal tube used for making hair curl SYN roller Her hair was in curlers.Examples from the Corpus
curler• Only use eyelash curlers if your lashes are very straight.• Even Beattie has hung up her curlers along with her telephone.• Try winding four or five large curlers into the crown to add height.• It was Cynthia, in a robe and gown with her hair full of curlers.• Pink curlers were rolled into her hair.• Alice came to the doorway pulling curlers from her hair.• Naturally straight, black hair was set at the crown on small curlers then gelled into two different shapes.• Don't be fooled into thinking you have to have curly styles if you use curlers - you don't. 