rheolydd

== Welsh == === Etymology === rheoli +‎ -ydd. === Pronunciation === (North Wales) IPA(key): /r̥ɛˈɔlɨ̞ð/ (South Wales) IPA(key): /r̥ɛˈoːlɪð/, /r̥ɛˈɔlɪð/ === Noun === rheolydd m (plural rheolyddion) controller, regulator (sciences) control (variable kept the same in an experiment) Synonym: newidyn rheolydd ==== Derived terms ==== newidyn rheolydd (“control variable”) rheolydd calon (“pacemaker”) rheolydd pell (“remote control (device)”) === Mutation ===