Celtic (pronounced with a hard “K” sound, and NOT the more commonly pronounced “S” sound, like the basketball team) is a style of tattooing with roots in the Medieval ethnic group of the same name. Though there is much debate regarding when and where Celtic society sprang up and how far it extended, what is largely regarded as the epicenter of Celtic culture encompasses modern-day Ireland, England, Scotland, and Wales. There was likewise a degree of cross pollination of Celtic symbols into Scandinavian Viking culture as well.
These designs are most commonly composed of mind-bending interlinking knot work, and sometimes bear stylized animals of the area in question. Even a seasoned tattoo veteran will be rendered cross eyed for days thereafter.