From Latin 'candidus' meaning 'white, pure, sincere'; Spanish and Italian form of Candidus.
Candido traces to the Latin candidus, meaning white, bright, pure, or radiant — the same root that gives English candid and candidate (Roman office-seekers wore white togas to signal purity of intent). The name was in use among early Christians as a mark of baptismal purity, and Saint Candidus, a soldier of the Theban Legion martyred around 286 CE, gave it martyrological weight in the Catholic tradition. It spread through the Romance languages as Cándido in Spanish, Candido in Italian and Portuguese, becoming a quiet fixture of devout families across southern Europe and Latin America.
Voltaire's 1759 philosophical novella Candide gave the name its most famous — and most ironized — literary life. The naive hero Candide stumbles through a catastrophic world while his tutor Pangloss insists that all is for the best in this best of all possible worlds. Voltaire's satire drove a wedge between the name's etymological innocence and the painful education the world administers to those who trust it too fully.
Candide became required reading across Europe and the Americas, and Leonard Bernstein's 1956 comic operetta adaptation ensured the story refreshed itself for new generations. In Spanish and Portuguese-speaking communities, Cándido/Candido remained in use throughout the 20th century largely independent of Voltaire's irony, carried by its sound and its religious associations. It has a luminous, old-world quality in English contexts — the kind of name that arrives with a complete cultural library already attached.