why do we have a silent k in english
Silent k In Old English, ⟨k⟩ and ⟨g⟩ were not silent in these words. Cognates in other Germanic languages show that the ⟨k⟩ was probably a voiceless velar plosive in Proto-Germanic (compare German Knecht to knight, Knoten to knot, etc. where the initial ⟨k⟩ is not silent); likewise, ⟨g⟩ was probably a voiced velar plosive (compare German Gnom to gnome, Gneis to gneiss, etc. where the initial ⟨g⟩ is not silent).
Kapu The opposite of kapu is noa, meaning "common" or "free".