Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
jointworm is a noun meaning "larva of chalcid flies injurious to the straw of wheat and other grains". It carries one recorded sense.
larva of chalcid flies injurious to the straw of wheat and other grains
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for jointworm come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.