seguro
/seˈɡuɾo/ · A1 · adv
sure
🔒 seguro = secure: both from Latin securus, se (without) + cura (care)
Latin securus meant free from care. English got secure and sure from it; Spanish got seguro. No worry means safe, and no doubt means certain. As an adverb, seguro on its own means surely, often softened to probably.