All Portuguese nouns are either masculine (m) or feminine (f). Generally, masculine nouns denote male human beings and animals and feminine nouns denote female human beings and animals. However, this doesn't help much when attempting to identify the gender nouns of inanimate, non-human or non-animal things. In such cases, "you just have to know." Most often, this means memorizing the gender of a particular noun.

There are, however, some clues that can be of great help in identifying the gender of some nouns. You can often determine the gender of a noun by the noun's ending or by the noun's meaning. Also, because many nouns have both masculine and feminine forms, you may also change the gender of many nouns by simply changing the ending.