See also: seid, Seid, séid, and sèid English Noun SEID (uncountable) (pathology) Abbreviation of systemic exertion intolerance disease. Anagrams Edis, Desi, eids, deis, ESDI, DESI, Ides, IEDs, EIDs, -side, side, sied, IDEs, ides, Eids, Dies, Dise, dies, desi, SideWikiwand - on Seamless Wikipedia browsing. On steroids.