Originally meant to be the girlfriend, friend, or supporter of skinheads
. It was stated that girls aren't supposed to be skinheads, but rather to help out the guys that are, but still wanted rank within the skinheads. So, they became skinbyrds. Some skinbyrds took on the look of skinheads, with the boots and shaved heads or chelsea hair, but most remained anonymous and chose to look 'normal'.
Some claim that there is no such thing as a female skinhead, and all that exists are skinbyrds. I suppose this though counts on what subgroup of skinheads you are.
Traditional skinheads believe in skinbyrds, and racist ones do too. Sharp and Rash skinheads think of women as skinheads, however.
See that girl over there, hanging out with all those skinheads, she's a skinbyrd.