Definition of Rubber by Merriam-Webster https://www.merriam-webster.com/dictionary/rubberProxy Highlight Define rubber: one that rubs. ... 1 a : one that rubs b : an instrument or object (as a rubber eraser) used in rubbing, polishing, ... Origin and Etymology of rubber. rubber - definition of rubber in English | Oxford Dictionaries https://en.oxforddictionaries.com/definition/rubberProxy Highlight ' .... Origin. Mid 16th century: from the verb rub + -er.