◎

◎ U+25CE, ◎ BULLSEYE ← ◍ [U+25CD] Geometric Shapes ● → [U+25CF]

Translingual

Symbol

◎

1. (chemistry, Daltonian symbol, obsolete) calcium ("lime")

   Technically, this should be red: ◎. May also be typeset ⊚ or ⦾, depending on which character matches the size of the other elements.

2. (cryptocurrencies) The symbol for cryptocurrency Solana.

   Synonym: (ISO 4217 code) SOL

3. (dated, engineering, GD&T) concentricity tolerance of the location of related features

Japanese

Etymology

Literally 二重丸(にじゅうまる) (nijūmaru, literally “two times circle”); a doubling of ○ for emphasis.

Symbol

◎(にじゅうまる) • (nijūmaru) 

1. very good (better than ○)
2. (cartography) city hall or other municipal building

   This use may be formatted with a heavy outer ring: