bonus genius

Learned borrowing from Latin bonus genius (literally “good spirit”).

bonus genius

1. A small wooden doll that is covered with a cape and made to vanish as part of a magic trick.
   • 1967, Henry Mayhew, London labour and the London poor:

     I'd pull out my cards and card-boxes, and the bonus genius or the wooden doll, and then I'd spread a nice clean cloth (which I always carried with me) on the table, and then I'd go to work.

   • 1979, Charles J. Pecor, The craft of magic: easy-to-learn illusions for spectacular performances:

     The trick of the little figure that vanishes, the Bonus Genius, as it was called, can be traced back to the seventeenth century, when this trick was recorded in one of the earliest magic books […]

2. (obsolete) A good spirit or angel, seen as influencing a person's decisions in a good way.

   Antonym: malus genius

   • 1638, Democritus Junior [pseudonym; Robert Burton], “Cure of Deſpaire by Phyſick, good counſell, comforts, &c.”, in The Anatomy of Melancholy. , 5th edition, Oxford, Oxfordshire: for Henry Cripps, →OCLC, partition 3, section 4, member 3, subsection 6, page 707:

     I dailie and hourelie offend in thought, word, and deed, in a relapſe by mine owne weakneſſe and wilfulneſſe, my bonus Genius, my good protecting angel is gone, I am falne from that I was, or would bee, worſe and worſe, […]