say it: theh-RIN
therein is an adverb meaning "(formal) in or into that thing or place". It is pronounced /ðɛˈɹɪn/ — theh-RIN. It carries one recorded sense.
Definitions, synonyms and semantic relations for therein come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.