Tooth  n. (pl. Teeth) 1 each of a set of hard bony enamel-coated structures in the jaws of most vertebrates, used for biting and chewing. 2 toothlike part or projection, e.g. The cog of a gearwheel, the point of a saw or comb, etc. 3 (often foll. By for) taste; appetite. 4 (in pl.) Force, effectiveness.  armed to the teeth completely and elaborately armed. Fight tooth and nail fight very fiercely. Get one's teeth into devote oneself seriously to. In the teeth of 1 in spite of (opposition or difficulty etc.). 2 contrary to (instructions etc.). 3 directly against (the wind etc.).  toothed adj. (also in comb.). Toothless adj. [old english]