A person (typically male) who takes pride in his appearance, dresses impeccably, goes for facials, expensive hair cuts and things of that nature. They are often assumed to be gay.

A man who is heterosexual, and yet is very feminine. Someone who is meterosexual can sometimes be mistaken for a person who is homosexual, because it is a stereotypical beleif that gay men are "feminine,"

A guy who is straight, dates girls, but takes a little more pride in his apperence.

A guy who is not gay, but pretty damn close.

Meterosexual (pronounced "Met-er-O sex-U-al") (short: Metero) is a colloquialism (popular modern slang) which means someone who dresses or is flamboyant in a manner that is stereotyped to homosexuals, but is in fact a heterosexual.
This may also be someone who is gay and flamboyant, but isn't open or doesn't consciously know. So when asked if they are gay they say "oh no, I'm Metero.", though, in reality, they are gay.

one who only has sex if measurements are made using the Metric system. probably somewhat insecure

What Jesus was. Jesus was totally a meterosexual because he got all the men to wash his feet.