rubber (n.)

"thing that rubs" (a brush, cloth, etc.), 1530s, agent noun from rub (v.). The meaning "elastic substance from tropical plants" (short for India rubber) first recorded 1788, introduced to Europe 1744 by Charles Marie de la Condamine, so called because it originally was used as an eraser.

Very useful for erasing the strokes of black lead pencils, and is popularly called rubber, and lead-eater. [entry for Caoutchouc in Howard, "New Royal Encyclopedia," 1788]

Meaning "overshoe made of rubber" is 1842, American English; slang sense of "condom" is by 1930s. Sense of "deciding match" in a game or contest is 1590s, of unknown signification, and perhaps an entirely separate word. Rubber stamp (n.) is from 1881; figurative sense of "institution whose power is formal but not real" is from 1919; the verb in this sense is from 1934. Rubber cement is attested from 1856 (from 1823 as India-rubber cement). Rubber check (one that "bounces") is from 1927.

Others are reading

Definitions of rubber from WordNet
rubber (n.)
an elastic material obtained from the latex sap of trees (especially trees of the genera Hevea and Ficus) that can be vulcanized and finished into a variety of products;
Synonyms: natural rubber / India rubber / gum elastic / caoutchouc
rubber (n.)
any of various synthetic elastic materials whose properties resemble natural rubber;
Synonyms: synthetic rubber
rubber (n.)
a contest consisting of a series of successive matches between the same sides;
he won three out of five games to take the rubber
rubber (n.)
an eraser made of rubber (or of a synthetic material with properties similar to rubber); commonly mounted at one end of a pencil;
Synonyms: rubber eraser / pencil eraser
rubber (n.)
contraceptive device consisting of a sheath of thin rubber or latex that is worn over the penis during intercourse;
Synonyms: condom / safety / safe / prophylactic
rubber (n.)
a waterproof overshoe that protects shoes from water or snow;
Synonyms: arctic / galosh / golosh / gumshoe
rubber (v.)
coat or impregnate with rubber;
Synonyms: rubberize / rubberise
rubber (adj.)
returned for lack of funds;
a rubber check
Synonyms: no-good