Where does “подпольный” come from?

подпольный (Russian) comes from Russian -ный, from Old Church Slavonic -ьнъ, from Proto-Slavic -ьnъ — -ish, -ic, -al, -ed; From adjectives.

подпольный (Russian): underground

Definitions

  1. underground

Ancestry of “подпольный”, step by step

StepLanguageWordMeaning
1Russian-ный-ish, -ic, -al, -ed
2Old Church Slavonic-ьнъish, -ic, -al, -ed
3Proto-Slavic-ьnъ-ish, -ic, -al, -ed; From adjectives
Every word from Proto-Slavic -ьnъ →Every word from Russian -ный →Every word from Old Church Slavonic -ьнъ →
подпольный — Etymology, Origin & Word History | Etymology Explorer