(dated) the area of high ethnic Tibetan populations that are outside of the area roughly equivalent to the Tibetan Autonomous Region, but inside of China

(organic chemistry) The simplest organic cyanide or nitrile, CH₃CN, formally derived from acetic acid

(organic chemistry, pharmacology) A synthetic alkaloid used as a local anesthetic.

One of a pair (the other of the pair being Tweedle-dee) of nominally different (often: but practically identical) things.