why do nouns have gender in some languages
Grammatical gender The division into genders usually correlates to some degree, at least for a certain set of nouns (such as those denoting humans), with some property or properties of the things that particular nouns denote. Such properties include animacy or inanimacy, "humanness" or non-humanness, and biological sex.
English plurals The plural morpheme in English is suffixed to the end of most nouns. Regular English plurals fall into three classes, depending upon the sound that ends the singular form:
Bracket Forms include round (also called "parentheses"), square, curly (also called "braces"), and angle brackets (also called "chevrons"); and various other pairs of symbols.
Limit of a function (the Dirichlet function) has no limit at any x-coordinate.