'Spinster' would be the female equivalent, however it carries negative connotations - it can be used as an insult because it can imply the woman is unmarriageable, rather than simply made a choice not to do so.
The fairly new term bachelorette is a mostly US term for a female bachelor.
A widow is female and a bachelor is male, so they are the opposite gender. A widow is not the female equivalent of a bachelor. It is the female equivalent of a widower. A spinster is the female equivalent of a bachelor.
In Chinese, we call a female bachelor as "Sheng Nv". Huh
It is known as different things in differnt parts of the world: Hen Party
Spinster means an unmarried female
The gender of a bachelor is male while a bachelorette is a female.
Bachelorette
The informal term for a female bachelor is bachelorette.(An earlier term was "spinster" which is seldom used today.)
* Both the male and female are called 'divorcees.'
Spinster
The Bachelor is a television program about finding a mate for the person.
spinster (female) or bachelor (male)
Bachelor