Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
teach-in is a noun meaning "an extended session (as on a college campus) for lectures and discussion on an important and usually controversial issue". It carries one recorded sense.
an extended session (as on a college campus) for lectures and discussion on an important and usually controversial issue
Definitions, synonyms and semantic relations for teach-in come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.