What is the meaning of Cyathus?

A Roman unit of liquid measure reckoned as the volume of 1⅔ Roman ounce of wine and equivalent to about 45 mL although differing slightly over time.

Synonym of ladle, especially a small one used for serving wine in ancient Greece and Rome.

Synonym of kyathos (an ancient ladle and serving beaker).

cyathus, Roman cup, a Roman unit of liquid measure equivalent to about 45 mL

ladle, especially a small wine ladle in Roman contexts

kyathos, a small wine ladle and serving beaker in ancient Greece and Rome

Source: wiktionary.org