(K’s, k’s)
1.
K is the eleventh letter of the English alphabet.
N-VAR
2.
K or k is used as an abbreviation for words beginning with k, such as ‘kilometre’, ‘kilobyte’, or ‘king’.
3.
K or k is sometimes used to represent the number 1000, especially when referring to sums of money. (INFORMAL)
I used to make over 40k.
NUM: usu num NUM