| K | Special K (cereal) | |
| K | Over (logging abbreviation) | |
| K | Que (Spanish) | |
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| K | King (playing cards, chess) | |
| K | Knowledge | |
| K | Black (in CMYK color space) | |
| K | Contract | |
| K | Killer (type of white blood cell) | |
| K | Okay | |
| K | Capital (economics) | |
| K | K-Mart (store) | |
| K | Carrying Capacity (population studies) | |
| K | Kerry (Irish car registration) | |
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| K | Cologne (auto license plate) | |
| K | Key Generator | |
| K | Knot | |
| K | Kirby | |
| K | Kindergarten (as in K-12) | |
| K | Eastern Ontario (postal code designation, Canada) | |
| K | Kompressor (band) | |
| K | Kappa (receptor) | |
| K | Kicker (football) | |
| K | Kelvin (thermodynamic temperature scale) | |
| K | Karat | |
| K | Conductivity | |
| K | Kosher (symbol on food labels) | |
| K | Kilo- (thousand) | |
| K | Curvature | |
| K | Lysine (amino acid) | |
| K | Permeability (physics) | |
| K | Cathode (electronics) | |
| K | Ketamine (animal tranquilizer/disassociative) | |
| K | Kalium (Potassium) | |
| K | Kilobyte | |
| K | Strikeout | |
| K | Korpus (Russian, building; used in postal addresses) | |
| K | Knit Stitch | |
| K | Kerrang! (British Magazine and TV Channel) | |
| K | Phylloquinone (vitamin) | |
| K | K Language (Unix-Based programming language) | |
| K | Kell Blood Group | |
| K | Key/Black (printing ink in CMYK model) | |
| K | OK/Okay | |
| K | Boltzman Constant | |
| K | Coefficient of Thermal Conductivity | |
| K | Kilohm (unit of electrical resistance; also seen as Kiloohm) | |
| K | Kiloohm (resistor; electronics schematics) | |
| K | Ludwig von Köchel (publisher of catalog of the works of Wolfgang Amadeus Mozart) | |
| K | Klebsiella Pneumoniae Serotype | |
| K | Federal Reserve Bank of Dallas, Texas (designates original point of circulation of a dollar bill) | |
| K | Keratometric Reading (contact lens fitting term) | |
| K | Kellogg's Corp (stock symbol) | |
| K | Confidential Cryptographic (TMINS) | |
| K | US Offices in China Stamp (Scott Catalogue prefix; philately) | |
| K | Tanker Aircraft Designation (US military, as in KC-10) | |
| K | Wreck Less Than $50 Damage (Alabama Public Safety radio code) | |
| K | Kritik (German: critique) | |