/pi tish"ee oh' prin sip"ee uy'/ ; Lat. /pe tee"ti oh' prdding kip"i ee'/ , Logic.
a fallacy in reasoning resulting from the assumption of that which in the beginning was set forth to be proved; begging the question.
[ 1525-35; petitio principii, trans. of Gk tò en archêi aiteîsthai the assumption at the outset ]