\Sure"ly\, adv. 1. In a sure or certain manner; certainly; infallibly; undoubtedly; assuredly. In the day that thou eatest thereof thou shalt surely die. --Gen. ii. 17. He that created something out of nothing, surely can raise great things out of small. --South. 2. Without danger; firmly; steadly; securely. He that walketh uprightly walketh surely. --Prov. x. 9.