1. A day on which good fortune or positive events occur; a day characterized by success, good luck, or favorable circumstances
Today was a lucky day; I won the lottery and got a promotion at work.
Hoje foi um dia afortunado; ganhei na loteria e recebi uma promoção no trabalho.
2. In superstitious or astrological contexts, a day considered to be auspicious or favorable for undertaking important activities
According to the astrologer, next Tuesday is a lucky day to start new projects.
Segundo o astrólogo, terça-feira próxima é um dia afortunado para iniciar novos projetos.