Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
sub-rosa is an adjective meaning "designed and carried out secretly or confidentially". It carries one recorded sense.
designed and carried out secretly or confidentially
“a sub-rosa report”
“has their under-the-table backing”
Definitions, synonyms and semantic relations for sub-rosa come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.