Where does “напольный” come from?

напольный (Russian) comes from Russian пол, from Old East Slavic полъ, from Proto-Slavic polъ, from Proto-Indo-European (s)pelH- — to split off, separate; to chop, to separate.

напольный (Russian): installed on the floor

Definitions

installed on the floor

Ancestry of “напольный”, step by step

Step	Language	Word	Meaning
1	Russian	пол	floor; sex, gender; short masculine singular of...
2	Old East Slavic	полъ	floor
3	Proto-Slavic	polъ	side, flank; half; member of a pair of options →...
4	Proto-Indo-European	(s)pelH-	to split off, separate; to chop, to separate

Every word from Proto-Indo-European (s)pelH- →Every word from Proto-Slavic polъ →Every word from Old East Slavic полъ →