さぞ・嘸sazo[1]atamadaka (head-high)

1. adverbsurely; certainly; no doubt; must
   さぞショックだったでしょう。↗

   It must have been a shock to you.

• SynonymさぞかしNeutralThe emphatic form of 「さぞ」, 'surely, no doubt', as in 「さぞかし寒かろう」. Stronger in tone and interchangeable with 「嘸」.
• SynonymさぞやWrittenAlso 'surely, no doubt', same meaning as 「さぞかし」, but more literary and slightly archaic; less common in daily speech.
• Related誠にまことにFormal'Truly, indeed', intensifying degree, as in 「誠に申し訳ない」, typically in formal settings. It has no conjectural sense and cannot replace 「嘸」.
• Related実にじつにFormal'Truly, really' as 「実に」: emphasizes a fact rather than guessing. 「嘸」 is followed by 「でしょう」 or similar, so the two are not interchangeable.
• RelatedまったくNeutral'Completely, really'; intensifies degree or negation, and on its own 「まったく」 is an exclamation of exasperation. No conjecture, so it cannot stand in for 「嘸」.
• Related本にほんにCasual'Really, truly', with a dialectal or old-fashioned flavor; confirms a fact, without the 「嘸」 sense of imagining someone else's situation.
• Related真にしんにFormalAs 「真に」: a polite 'truly, sincerely', as in 「誠にありがとうございます」. It only intensifies degree; unlike 「嘸」, it does not express conjecture.

Use 「嘸（さぞ）」 to imagine how someone must be feeling or how things must be, followed by a conjectural ending, as in 「さぞお疲れでしょう」; for emphasis say 「さぞかし」. 「誠に」 and 「全く」 express no conjecture: they intensify, and 「全く」 can also voice exasperation.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. （下したに推量すいりょうの語ごを伴ともない）きっと。さだめて。