The bull in bullshit is unrelated the bull meaning a ludicrous jest It is as suggested a portmanteau of bull n 1 in the OED the male of any bovine animal and shit According to the OED the ludicrous jest version n 4 is is not derived from Papal Bull No foundation appears for the guess that the word originated in a contemptuous allusion to papal edicts nor for the assertion of the British Apollo No 22 1708 that it became a Proverb from the repeated Blunders of one Obadiah Bull a Lawyer of London who liv d in the Reign of K Henry the Seventh I m sorry but I don t know how to cite the OED as I have the electronic version Oh wait I take that back This is how they have in the OED f bull n 1 shit n 1 1 Rubbish nonsense bull n 4 3 First they have it in the n 1 sense then in the n 4 sense just below so I m not sure