| Acronym | Meaning |
| K | Confidential Cryptographic (TMINS) |
| K | Federal Reserve Bank of Dallas, Texas (designates original point of circulation of a dollar bill) |
| K | Key Generator |
| K | Knot |
| K | Korpus (Russian, building; used in postal addresses) |
| K | Tanker Aircraft Designation (US military, as in KC-10) |
| K | US Offices in China Stamp (Scott Catalogue prefix; philately) |
| K | Wreck Less Than $50 Damage (Alabama Public Safety radio code) |