What is a "Character with an Ambigious Gender"?

(NOTE: THIS CHARACTER IS USALLY AN ALIEN, MONSTER, OR ROBOT)

This is a character who falls squarely in the middle of the male-female divide... except that no-one can decide which side the character actually belongs on. Lots of subterfuge always follows, as everyone follows him/her around to try and determine his/her Gender once and for all. This person is eaither Male, Female, Both genders, or Neither Genders.

a real life example of this is actually most babies, NOW all babies are Male or Female but it's very hard to tell what a baby animals gender is because it's body is not fully devloped

I like this article short and to the point.

Good examples of when the gender is unknown. In some cases is never revealed and is unnecessary for the story