- a vector on the z-axis, having length 1 unit.
- Boltzmann constant.
- the eleventh letter of the English alphabet, a consonant.
- any sound represented by the letter K or k, as in bilk, kit, or sick.
- something having the shape of a K.
- a written or printed representation of the letter K or k.
- a device, as a printer's type, for reproducing the letter K or k.
- the number 1000: The salary offered is $20K.
- kilometer, especially in a footrace or wheelchair race on a road or track: She’s training to run her first 10K this summer.
- king.
- Kelvin.
- Köchel listing.
- kindergarten: a K–12 boarding school.
- kitchen.
- the eleventh in order or in a series.
- Computers.
- the number 1024 or 210: A binary 32K memory has 32,768 positions.
- kilobyte.
- strikeout; strikeouts.
- kaon.
- lysine.
- potassium.
- carrying capacity.
- capacity.
- karat.
- kilogram; kilograms.
- king.
- knight.
- knot.
- kopeck.
- kip; kips.
- Knight.
- kwacha.
- kilo(s)
- the unit vector along the z-axis
- the 11th letter and 8th consonant of the modern English alphabet
- a speech sound represented by this letter, usually a voiceless velar stop, as in kitten
- See five Ks
- Köchel: indicating the serial number in the catalogue (1862) of the works of Mozart made by Ludwig von Köchel (1800–77)
- kelvin(s)
- king
- potassium
- kaon
- currency
- kina
- kip
- kopeck
- kwacha
- kyat
- one thousand
- computing
- a unit of 1024 words, bits, or bytes
- (not in technical usage) 1000
- Cambodia (international car registration)