UUD Views 6 meanings found UUD can refer to an undergraduate university division, the Russian city of Ulan‑Ude, a UUencoded file archive, or the proton’s quark composition in physics, among other uses. International Ujung-Ujungnya Duit Undang Undang Dasar Academic & Science Undergraduate University Division Proton, two up quarks (u) and one down quark (d) Regional Ulan-Ude, Russia Computing UUencode Decoded file archive ( ASCII)