K vs large integer

K and large integer both are nouns.

Word	Noun	Adjective	Verb	Adverb
K	Yes	No	No	No
large integer	Yes	No	No	No

As nouns, large integer is a hypernym of K; that is, large integer is a word with a broader meaning than K:

K (noun)	large integer (noun)
street names for ketamine	an integer equal to or greater than ten
the 11th letter of the Roman alphabet
a unit of information equal to 1024 bytes
a unit of information equal to 1000 bytes
the basic unit of thermodynamic temperature adopted under the Systeme International d'Unites
the cardinal number that is the product of 10 and 100
a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite