notadictionary.com
昔怖い上司に「どうしてミスするの？」って問い詰められ、
→ “"Why do you make mistakes?" I was grilled by my scary boss back in the day,”
昔 mukashi = back in the day (noun/time adverb)
怖い kowai = scary / frightening (adjective)
上司 jō¹shi = boss / superior (noun)
上 ue = up / above
司 shi = to govern / director
に ni = by / to (particle indicating target of action)
「 = [opening quotation mark]
どうして dō¹shite = why (phrase)
どう dō¹ = how
して shite = to do (te-form of suru)
ミス misu = mistake / error (loanword from English 'miss')
する suru = to do (verb)
の no = marker for emphasis or softening question (sentence-ending particle)
？」 = [closing quotation mark]
って tte = quoting marker / colloquial connector (contraction of to iu)
問い詰められ toitsumerare = was grilled / interrogated (passive form of toitsumeru)
問 toi = question
い i = vowel sound extension
詰 tsu = pack / crowd
め me = intensifier
ら ra = passive auxiliary stem
れ re = passive auxiliary ending
、 = [comma]
