"And he causeth all, both small and great, rich and poor, free and bond, to receive a mark in their right hand, or in their foreheads." -Revelation 13:16

Dictionary definition of "tattoo":

n. pl. tat·toos

1. A permanent mark or design made on the skin by a process of pricking and ingraining an indelible pigment or by raising scars.
2. A design made on the skin with a temporary dye such as henna or ink.