Easton's Bible Dictionary
(Revelation 4:3, R.V., "sardius;" Hebrews `odhem; LXX., Gr. sardion, from a root meaning "red"), a gem of a blood-red colour. It was called "sardius" because obtained from Sardis in Lydia. It is enumerated among the precious stones in the high priest's breastplate (Exodus 28:17; 39:10). It is our red carnelian.
Noah Webster's New International Dictionary of the English Language
1. (n.) Any one of several small species of herring which are commonly preserved in olive oil for food, especially the pilchard, or European sardine (Clupea pilchardus). The California sardine (Clupea sagax) is similar. The American sardines of the Atlantic coast are mostly the young of the common herring and of the menhaden.
2. (n.) See Sardius.