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-interval is a noun meaning "an interval that is included in another interval". It carries one recorded sense.
an interval that is included in another interval
Definitions, synonyms and semantic relations for sub-interval come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.