(gum) noun
1. An amorphous, brittle, colloidal mass resulting from the drying of the exuded sap of trees or shrubs. True gums are complex hydrocarbons; they are usually soluble in water, but not in alcohol, ether, and the oils; but the name is popularly applied also to true resins and to gum resins, especially when used as mucilage, etc.
2. The gum tree.
3. Rubber.
4. plural U.S. Dial. Rubber overshoes; also, automobile tires.
5. A preparation of some natural gum (as cherry gum or balsam of Tolu), or some other tenacious substance, flavored and sweetened for use as a masticatory: also chewing gum.
6. U.S. Dial. A section of a gum tree made into a well-curb, a watering trough, a bin, etc.; also, a beehive made of a similar hollow log.
7. Any sticky, viscous substance.
8. The adhesive wash on the reverse side of postage stamps.
—v. gummed, gum·ming v.t.
1. To smear gum.
2. To stiffen or unite with gum.
—v.i.
3. To exude or form gum.
4. To become stiff and sticky.
—to gum up U.S. Slang To bungle or ruin. [<OF gomme <L gummi <Gk. kommi]
—gum′mer noun

(gum) noun Anat.
The fleshy tissue that covers the alveolar arches of the jaws and invests the necks of the teeth. ♦ Collateral adjective: gingival.
—v.t. gummed, gum·ming To chew with the gums: He gums his food. [OE goma inside of mouth]