Ichthys

Ichthys (also Ichthus or Ikhthus /ˈɪkθəs/), from the Koine Greek word for fish: ἰχθύς, (capitalized ΙΧΘΥΣ or ΙΧΘΥϹ) is a symbol consisting of two intersecting arcs, the ends of the right side extending beyond the meeting point so as to resemble the profile of a fish, used by early Christians as a secret Christian symbol and now known colloquially as the "sign of the fish" or the "Jesus fish."