ᴱQ. kambo “cellar, cave, vault” appeared in the Qenya Lexicon of the 1910s derived from the root ᴱ√KAVA, also the basis of ᴱQ. kava- “dig” (QL/45).

Neo-Quenya: Derivatives of the early root ᴱ√KAVA are no longer suitable for Neo-Quenya, as both √KAM and √KAB have very different meanings in later writings, but I think this word may be adapted as ᴺQ. sampo, reconceived as a derivative of √SAP “dig”. In the Qenya Lexicon, ᴱQ. sambo was “cave, hollow” along with variant ᴱQ. sampe (QL/82), but there are plenty of other cave words in Quenya, so using sampo for “cellar, vault” seems better to me.