Denshi Jisho — Online Japanese dictionary

嘸 さぞ I am sure; certainly; no doubt
Common word, Adverb, Usually written using kana alone 
嘸や さぞや surely; certainly
Adverb, Usually written using kana alone 
嘸かし さぞかし certainly; surely
Adverb, Usually written using kana alone 

You can also

Look up kanji details for 嘸 さぞや.

Try a Yahoo Jisho search for 嘸 さぞや .
Try a Goo Jisho search for 嘸 さぞや .
Try a Google search for 嘸 さぞや .