A property of nouns and pronouns.
A noun can have one of three genders, masculine, feminine, and neuter. Gender is never male or female; that is
sex.
The gender of a noun may have little or no relation to the
sex of its bearer. For example, in German, the word for
dog is der Hund, which has masculine gender. A
dog may be male or female, but the word for
dog has masculine gender.
Radical feminists, effeminate men, and extremely ignorant people use the word to mean
sex. They also ignorantly believe that the pronoun HE, when used to refer to someone of unknown
sex, is offensive. Instead, they ignorantly and incorrectly use the word THEY to refer to a single person of unknown
sex. Notice that French, German, Spanish, and other people have no trouble at all distinguishing sex and gender. A German is never offended by the word ER used to refer to someone of unknown
sex, even though ER also means HE. That's because Germans are intelligent enough to know the difference between gender and
sex, and that gender may have little to do with
sex.
Even well-meaning organizations ask for you gender on applications now, but only out of ignorance. They surely want to know if you are male or female, not whether you enjoy eating
butt or prancing on floats in parades.