- ○ まる
- OK; correct; yes; supported; available (like
✔
; note that the check mark usually means "wrong" in Japanese examinations) - masked/censored character (like
*
in English used to mask characters in certain words; see this) - rival horse; second likely to win (horse race; favorite horse is marked with
◎
) - win; victory; 白星 (when used as opposed to 黒星 =
●
= lose)
- OK; correct; yes; supported; available (like
- × ばつ、ぺけ、ばってん
- NG; wrong; no; unsupported; unavailable
- masked/censored character (mainly for sexual reasons; cf: ちょめちょめ)
- multiplication (math)
- lose (game)
- dead; extinct; obsolete (word, species, person; like
†
in English) - used to denote romantic relationships, especially in yaoi fandom (like "slash"
/
in English) - finished (calendar, event)
- △ さんかく
- partially OK; partially supported; nearly sold out; between ○ and ×; questionable
- second move; 後手 (in shogi, when used as opposed to
▲
= first move; sometimes inverted (▽
)) - negative value/earnings (finance, when positive values are marked with nothing)
- money gain; increase (stock market, when used as opposed to
▲
= loss) - dark horse; third likely to win (horse race)
- □ しかく
- unavailable character; glyph missing (see: 豆腐 and geta symbol)
- full-width space (as opposed to the dot
・
used to denote half-width (ascii) spaces)
And these symbols can be used as the casual placeholder for other arbitrary words/characters. (See this)
As you can see, depending on the context, filled symbols often mean the opposite things to the unfilled ones.