Previously, this term has been used, like batcaver, as a mid-80's description of a fan dressing up goth and appreciating punk, grunge and dark underground music in general. Today you just might find a batchic sipping a martini at an upscale bistro. Black is still the colour of choice for batchic apparel.
There has been a current retro-appreciation for batchic-iness, if only for the kitch that this term has come to be associated with, in relation to the Batman superhero comic book character, as created by Bob Kane. A batchic, in this case, is a fan of the Batman comic book series, and/or of the Warner Brothers' Batman animation series.
::"i just couldn't go face the world without dressing in my batchic black."
::" what's with that batchic? she lives and breathes 'Batman Beyond?'"