unconstitutional Syllabification: (un·con·sti·tu·tion·al)Pronunciation: /ˌənˌkänstəˈt(y)o͞oSHənl/Translate unconstitutional | into French | into Italian Definition of unconstitutional adjective not in accordance with a political constitution, especially the US Constitution, or with procedural rules. Derivatives unconstitutionalityPronunciation: /-ˌt(y)o͞oSHəˈnalətē/ noun unconstitutionally adverb unconstitutional in other Oxford dictionaries Definition of unconstitutional in the British & World English dictionary