Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
autoinjector is a noun meaning "a hypodermic syringe to use in injecting yourself with a liquid". It carries one recorded sense.
a hypodermic syringe to use in injecting yourself with a liquid
“United States troops now carry atropine and autoinjectors in their first-aid kits to use in case of organophosphate nerve agent poisoning”
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 autoinjector come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.