Lewis Short
(adverb) : quant-ŏpĕrē (contr. form, for which, in recent editions, the MS. form quantō ŏpĕre is restored)
* How greatly, how much (class.): dici non potest, quanto opere gaudeant,Cic. Att. 14, 6, 2; id. Tusc. 3, 3, 6. —After tanto opere, as: neque enim tanto opere hanc a Crasso disputationem desiderabam, quanto opere, etc.,Cic. de Or. 1, 35, 164; v. quantus.
Charlton T. Lewis, Charles Short, A Latin Dictionary