Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
nonreturnable is an adjective meaning "that may not be returned". It carries one recorded sense.
that may not be returned
“nonreturnable bottles cannot be exchanged for a deposit”
“sale merchandise is nonreturnable”
Definitions, synonyms and semantic relations for nonreturnable come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. .