(1.) A precious gem (Hebrews yahalom', in allusion to its hardness), otherwise unknown, the sixth, i.e., the third in the second row, in the breastplate of the high priest, with the name of Naphtali engraven on it (Exodus 28:18; 39:11; R.V. marg., "sardonyx.")

(2.) A precious stone (Hebrews shamir', a sharp point) mentioned in Jeremiah 17:1. From its hardness it was used for cutting and perforating other minerals. It is rendered "adamant" (q.v.) in Ezek. 3:9, Zechariah 7:12. It is the hardest and most valuable of precious stones.

Noah Webster's New International Dictionary of the English Language

1. (n.) A precious stone or gem excelling in brilliancy and beautiful play of prismatic colors, and remarkable for extreme hardness.

2. (n.) A geometrical figure, consisting of four equal straight lines, and having two of the interior angles acute and two obtuse; a rhombus; a lozenge.

3. (n.) One of a suit of playing cards, stamped with the figure of a diamond.

4. (n.) A pointed projection, like a four-sided pyramid, used for ornament in lines or groups.

5. (n.) The infield; the square space, 90 feet on a side, having the bases at its angles.

6. (n.) The smallest kind of type in English printing, except that called brilliant, which is seldom seen.

7. (a.) Resembling a diamond; made of, or abounding in, diamonds; as, a diamond chain; a diamond field.