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-assembly is a noun meaning "a unit assembled separately but designed to fit with other units in a manufactured product". It carries one recorded sense.
a unit assembled separately but designed to fit with other units in a manufactured product
Definitions, synonyms and semantic relations for sub-assembly come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.