Portuguese English
Segunda-Feira or 2ª/2ªs = Monday
Terça-Feira or 3ª/3ªs = Tuesday
Quarta-Feira or 4ª/4ªs = Wednesday
Quinta-Feira or 5ª/5ªs = Thursday
Sexta-Feira or 6ª/6ªs = Friday
Sabado = Saturday
Domingo = Sunday
Feriado = Public Holiday
Feira = Fair/Market
Sabado - Portuguese wikipedia shows this deriving from the Latin word sábbătum and the hebrew word for the Sabbath.
Domingo - Wikipedia suggests that this originates from the Catholic liturgy and refers to the "Day of the Lord."
See:
http://pt.wikipedia.org/wiki/S%C3%A1bado
&
http://pt.wikipedia.org/wiki/Domingo
