Editing Glossary of chess problems (section)

== O ==
{{glossary}}

{{term|term= obtrusive piece |content = obtrusive piece {{anchor|Obtrusive piece|obtrusive pieces}} }}
{{defn|defn= A piece in a chess problem that is legally placed and could only have been created through promotion. It does not include pieces promoted after the initial problem position.}}

{{term|term= orthochess |content = orthochess {{anchor|Orthochess|ortho-chess|Ortho-chess}} }}
{{defn|defn= Synonym for ''[[#orthodox chess|orthodox chess]]''.<ref>Pritchard (2007), p. 242. ''Orthochess''.</ref>}}

{{term|term= orthodox chess |content = orthodox chess {{anchor|Orthodox chess}} }}
{{defn|defn= Chess according to [[FIDE]]'s ''The Official Laws of Chess'';<ref>Hooper & Whyld (1996), p. 285. ''orthodox chess''.</ref> see [[Rules of chess]].}}

{{glossary end}}