Where does “nícon” come from?

nícon (Old Irish) comes from Old Irish ní, from Proto-Celtic nīs, from Proto-Indo-European ne h₁ésti — is not.

nícon (Old Irish): not

Definitions

Step	Language	Word	Meaning
1	Old Irish	ní	not; is not, isn’t; something, anything
2	Proto-Celtic	nīs	—
3	Proto-Indo-European	ne h₁ésti	is not

nícon — Etymology, Origin & Word History | Etymology Explorer