Where does “намертво” come from?

намертво (Russian) comes from Russian мертво́, from Russian мёртвый, from Proto-Slavic mьrtvъ, from Proto-Indo-European mr̥twós, from Proto-Indo-European mer- — to die; to disappear; sea, lake, wetland.

намертво (Russian): tightly, fast, permanently

Definitions

tightly, fast, permanently

Ancestry of “намертво”, step by step

намертво traces back through two separate lines of ancestry.

via Russian мертво́

Step	Language	Word	Meaning
1	Russian	мертво́	—
2	Russian	мёртвый	dead; lifeless; dead man
3	Proto-Slavic	mьrtvъ	dead
4	Proto-Indo-European	mr̥twós	dead
5	Proto-Indo-European	mer-	to die; to disappear; sea, lake, wetland

via Russian на́

Step	Language	Word	Meaning
1	Russian	на́	here you go! (encouraging someone to accept something, used when giving or providing something, i.e., "take it!", "here you goǃ")
2	Proto-Slavic	na	on; concerning; onto
3	Proto-Indo-European	h₂en-	on, onto

Every word from Proto-Indo-European mer- →Every word from Proto-Indo-European mr̥twós →Every word from Proto-Slavic mьrtvъ →