Where does “niechtórny” come from?

niechtórny (Polish) comes from Polish niektóry, from Old Polish niektóry, from Old Polish nie-, from Old Polish nie, from Proto-Slavic ne, from Proto-Balto-Slavic nē, from Proto-Indo-European né — not; no.

Ancestry of “niechtórny”, step by step

Step	Language	Word	Meaning
1	Polish	niektóry	some
2	Old Polish	niektóry	some
3	Old Polish	nie-	generic negation prefix, used for adjectives, adverbs and participles; un-, dis-, -less, non
4	Old Polish	nie	negation particle; no, not
5	Proto-Slavic	ne	not
6	Proto-Balto-Slavic	nē	not
7	Proto-Indo-European	né	not; no

Every word from Proto-Indo-European né →Every word from Proto-Balto-Slavic nē →Every word from Proto-Slavic ne →