A dumpst is a person who shows extreme stupidity or thick-headedness, or someone who is just plain stupid. It is also OK to say "What a dumpst!" in a period of quiet in a large crowd. Plural of dumpst is dumpstii.
Often misspelled (sometimes on purpose) as "dumptz".
"What a dumpst!"
"She sure was a dumpst!"
"I am surrounded by dumpstii!"