agate

plural agates

1. countableuncountablechemistryA semitransparent, uncrystallized silicate mineral and semiprecious stone, presenting various tints in the same specimen, with colors delicately arranged and often curved in parallel alternating dark and light stripes or bands, or blended in clouds; various authorities call it a variety of chalcedony, a variety of quartz, or a combination of the two.

   Yes: living among the cohabations^([sic]) of Faust himself, among the litharge and agate and hyacinth and pearls.

   1947, Malcolm Lowry, Under the Volcano, New York: Reynal & Hitchcock, page 86

   1 more example

   The ends of the veil, drawn over her head, were embroidered with silver; she had long gold ear-rings; to a rich and large gold chain was suspended a cross set with precious stones; and over the arm of her chair hung a rosary of agate beads.

   1831, L[etitia] E[lizabeth] L[andon], chapter I, in Romance and Reality. […], volume III, London: Henry Colburn and Richard Bentley, […], →OCLC, page 9

2. USdateduncountablemediaThe size of type between pearl and nonpareil, standardized as 5+¹⁄₂-point.

   Synonyms: ruby

3. countablemediaOne fourteenth of an inch.
4. countableobsoleteA diminutive person; so called in allusion to the small figures cut in agate for rings and seals.
5. countableA tool used by gold-wire drawers, bookbinders, etc.;—so called from the agate fixed in it for burnishing.
6. countableA marble made from agate.

   Synonyms: aggie

7. countableplural normallyslanguncountableA testicle.

1. not comparableobsoleteOn the way; agoing.

   I'm fear'd you have some ill plans agate.

   1847 October 16, Currer Bell [pseudonym; Charlotte Brontë], Jane Eyre. […], volume (please specify |volume=I to III), London: Smith, Elder, and Co., […], →OCLC

   1 more example

   Go to it then hardily, and let us be agate.

   1554, Interlude of Youth