- (metrology) Symbol for terawatt, an SI unit of power equal to 1012 watts.
- The ISO 3166-1 two-letter (alpha-2) code for Taiwan.
TW (plural TWs)
- (gemstones) Initialism of . (in carats).
- (pharmacology) Initialism of .
- (LGBT) Initialism of .
- Initialism of .
Perhaps from the Telex input method where the W key is pressed to type the letter ư or to add the diacritical side horn to an already typed u to form the ư, and intended to be this way to distinguish from tư as an actual word, or to make "non-word" abbreviations easier to type with common keyboard programs that do not recognize them as Vietnamese.
- Abbreviation of .