CEI CEI may stand for : Conferenza Episcopale Italiana Central European Initiative Cleveland Electric Illuminating Co . Competitive Enterprise Institute Cycle Engineers ' Institute , a screw thread pattern ( see British Standard Whitworth , which includes information on topic ) See also CEI Chief Executive Instruction Look up CEI in Wiktionary , the free dictionary . This page disambiguates a three-character combination . If an article link referred you to this page , you may wish to change the link to point directly to the intended article . Categories : Lists of three-character combinations In other languages : Italiano 