oitavo

Oitavo is a Portuguese adjective and noun form meaning eighth, used to express order, position or quantity. The masculine form is oitavo, the feminine form is oitava; the plural forms are oitavos and oitavas, depending on gender. It functions as an ordinal numeral and can modify masculine or feminine nouns accordingly.

In common usage, oitavo indicates the eighth item in a sequence. For example, o oitavo dia refers to the eighth day, and ele ficou em oitavo lugar means he finished in eighth place. In calendrical terms, o oitavo mês do ano is agosto, the eighth month in the Gregorian calendar.

In music, the related noun oitava denotes an octave, the interval spanning eight notes. The expression oitava justa is used to describe a perfect octave in musical theory, and oitavas can appear in discussions of pitch ranges and vocal or instrumental ranges.

In sports and competitions, the term appears in expressions such as oitavas de final, which refers to the round of 16 in tournaments, indicating the stage where 16 teams compete for advancement.

As a fraction, oitavo also appears in mathematical contexts meaning 1/8; the singular is um oitavo and the plural dois/três/oitavos can describe multiple eighths.

Etymologically, oitavo derives from Latin octavus, through the development of Portuguese. It is closely related to oitava in the musical sense and to oito as the root number eight.