The latin letter k is used in math as a variable. It commonly appears as an index variable for matrices along with the other letters i, j, and l.
Symbol  Format  Data 

k  Unicode 

TeX 


SVG 
A variable is a core concept in algebra where a symbol, usualy a lower case latin letter, is used as a placeholder in a math expression.
The Latin Alphabet is a collection of 26 symbols that form the basis of the English language. The alphabet's symbols are used throughout mathematics to represent variables, constants, and coeffecients.
The capital Latin letter K.