Mattiaci

thumb|right|400px|Rhine frontier of the Roman empire, 70 AD, showing the location of the Mattiaci in Germania Magna near the Rhine. Roman territory is shaded dark

The Mattiaci were by Tacitus recorded as an ancient Germanic tribe and related to the Chatti, their Germanic neighbors to the east. There is no clear definition of what the tribe's name meant. The Dictionary of Greek and Roman Geography suggests that the name is derived from a combination of 'matte', meaning 'a meadow', and 'ach' (pronounced with the 'ch' as in 'loch'), signifying water or a bath.