Two letter words are frequently abbreviations.
Ka -- a Cirque du Soleil show
Kb -- kilobyte
KC -- Kansas City
K.D. -- Singer Lang
KE -- kinetic energy
kg -- kilogram
ki -- Chinese life force
kJ -- kilojoule
kl -- kiloliter
km -- kilometer
KN -- the King's knight
KO -- knockout
KP -- kitchen police
Kr -- krypton
KS -- Kansas
Kt -- knight
Ku -- kurchatovium
kV -- kilovolt
kW -- kilowatt
KY -- Kentucky
Kick
A two word thing beginning with the letter k is kami kazi.
kangaroos
khaki, kicks
There are no four letter words that begin with k and include the letter z.
I think there is none
Kinetic and kleptomaniac begin with the letter k. They end with the letter c.
haddock
Killshot
knapsacks
keynote
mcdonalds
broomstick