the word "tooth" has a remarkably stable history, tracing a direct line from the proto-indo-european root "h₃dent-" into the germanic branch of the language family. its old english form "tōþ" underwent the expected sound changes, such as the germanic consonant shift, to arrive at its modern spelling and pronunciation. the core concept of a hard, bony protrusion used for biting has remained constant for millennia, even as the word's application expanded metaphorically to describe similar projecting parts on tools like saws and gears. this enduring linguistic form reflects the fundamental and unchanging biological reality the word describes.

the modern english word "tooth" is a direct descendant from the old english "tōþ" (plural "tēþ"), which is of germanic origin. it is related to dutch "tand" and german "zahn". the old english form derives from proto-germanic "tanþs", which in turn comes from the proto-indo-European root "h₃dónts", "h₃dent-" (tooth). this root is also the source for latin "dens" (genitive "dentis"), greek "odous" (genitive "odontos"), and sanskrit "dán".