Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
thermochemistry is a noun meaning "the branch of chemistry that studies the relation between chemical action and the amount of heat absorbed or generated". It carries one recorded sense.
the branch of chemistry that studies the relation between chemical action and the amount of heat absorbed or generated
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 thermochemistry come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.