- Chess knight
- Knight of (the Order of) the Thistle
- Knight (or Knights) Templar
- Nautical knot (measurement)
Of or relating to the boundary between the Cretaceous and Tertiary periods, characterized by a mass extinction in which all nonavian dinosaur species perished and by a layer of rock enriched with iridium thought to have originated in one or more asteroid impacts.
Origin of K-TK, short for Cretaceous (used instead of C, because that letter is often used as an abbreviation of Cambrian) + Tertiary.
- (colloquial) Katie (given name)
- Central Kalimantan, a province of Indonesia.