任意 (にんい)optional; voluntary; arbitrary

optional; voluntary; arbitrarynouns which may take the genitive case particle 'no', adjectival nouns or quasi-adjectives (keiyodoshi)
arbitrarynouns which may take the genitive case particle 'no', adjectival nouns or quasi-adjectives (keiyodoshi)

任意, its kanji, and other words that share them.Open this graph

Kanji in 任意

責任せきにんduty; responsibility (incl. supervision of staff)
就任しゅうにんassumption (of office); taking up (a post)
辞任じにんresignation (from a position)
任期にんきterm of office
常任じょうにんstanding; regular
後任こうにんsuccessor
責任者せきにんしゃperson in charge (including a supervisory role for other staff); person responsible for ...
不信任ふしんにんnon-confidence; lack of confidence
合意ごうい(coming to an) agreement; consent
意向いこうintention; idea
意味いみmeaning; significance
意見いけんopinion; view
意思いしintention; wish
意欲いよくwill; desire
意識いしきconsciousness
決意けついdecision; determination

See how 任意 connects to the rest of Japanese.