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Nescio
"Nescio", Latin for "I don't know", was the pen name of Dutch writer Jan Hendrik Frederik Grönloh, who was born on June 22, 1882, in Amsterdam and died on July 25, 1961, in Hilversum, also in the Netherlands. Grönloh was a businessman by profession, but as Nescio he is mainly remembered for the three novellas De uitvreter (The Freeloader), Titaantjes (Little Titans) and Dichtertje (Little Poet). His reputation as an important Dutch writer was only established after his death.
Usage examples of "nescio".
The compounds of mercury have yielded their place as drugs of all work, and specifics for that very frequent subjective complaint, nescio quid faciam,--to compounds of iodine.
Hosmannus in his work of thirty years, saith plainly, Nescio quid sit.