Deemer is from Old English deman ('to judge, deem'), from dom ('judgment, doom'), plus the agentive suffix -er. Native Germanic in origin. The ancestry passes through Old English deman, Old English dom, and Proto-Germanic *dōmaz. The suffix -er marks an agent, instrument, or associated person, so the English form is shaped by recognizable word formation as well as by its inherited or borrowed base. In present use as a noun, it means "one who deems or judges (archaic)", keeping the historical formation close to the word's ordinary semantic work. Related words include deem, deemster, and doom.