Cotton on

Origin of: Cotton on

Cotton on

To cotton on is to understand or realise that something is the case and this particular usage dates from the early 20th century. The OED gives several earlier citations for cotton together or cotton with meaning to get on well together or to be drawn together, most of which date from the 16th century. All these meanings, however, ultimately derive from the way cotton sticks to clothing. Therefore, as cotton adheres to clothing so do we adhere to or cotton on to people, ideas etc.