mid 16th cent.: from the verb rub + -er. The original sense was 'an implement (such as a hard brush) used for rubbing and cleaning'. Because an early use of the elastic substance (previously known as caoutchouc) was to rub out pencil marks, rubber gained the sense 'eraser' in the late 18th cent. The sense was subsequently (mid 19th cent.) generalized to refer to the substance in any form or use, at first often differentiated as India rubberlate 16th cent.: of unknown origin; early use was as a term in bowls
