n. 1. One who, or that which, rubs. Specifically: (a) An instrument or thing used in rubbing, polishing, or cleaning. (b) A coarse file, or the rough part of a file. (c) A whetstone; a rubstone. (d) An eraser, usually made of caoutchouc or a synthetic rubber[ 4 ]. (e) The cushion of an electrical machine. (f) One who performs massage, especially in a Turkish bath. (g) Something that chafes or annoys; hence, something that grates on the feelings; a sarcasm; a rub. Thackeray. [ 1913 Webster ]

2. In some games, as bridge or whist, the odd game, as the third or the fifth, which decides the winner when there is a tie between the players; as, to play the rubber; also, a contest determined by the winning of two out of three games; as, to play a rubber of whist. Beaconsfield. “A rubber of cribbage.” Dickens. [ 1913 Webster ]

3. India rubber; caoutchouc; gum elastic; -- also called natural rubber. [ 1913 Webster +PJC ]

4. Any substance, whether natural or synthetic, resembling India rubber with respect to its elasticity[ 1 ]. [ PJC ]

5. A low-cut overshoe made of natural or synthetic rubber[ 4 ], serving to keep the feet and shoes dry when walking in the rain or on a wet surface; -- usually used in the plural. [ 1913 Webster ]

6. A condom. [ Slang ] [ PJC ]

Antimony rubber, an elastic durable variety of vulcanized caoutchouc of a red color. It contains antimony sulphide as an important constituent. --
Hard rubber, a kind of vulcanized caoutchouc which nearly resembles horn in texture, rigidity, etc. --
India rubber, caoutchouc. See Caoutchouc. --
Rubber cloth, cloth covered with caoutchouc for excluding water or moisture. --
Rubber dam (Dentistry), a shield of thin sheet rubber clasped around a tooth to exclude saliva from the tooth. [ 1913 Webster ]

n. A closed loop of rubber usually having a thin rectangular cross-section; also called elastic band; -- it varies in length from the circumference of a finger to several inches, and is usually used to hold several objects together temporarily, by the tension exerted when the band is stretched and fitted around the objects to be held; as, to hold a pack of cards together with a rubber band. [ PJC ]

v. t. To coat or impregnate with rubber or a rubber solution or preparation, as silk. [ Webster 1913 Suppl. ]