(Science: zoology) From Pray, Praying insect, locust, or mantis, a mantis, especially Mantis religiosa. See Mantis. Praying machine, or Praying wheel, a wheel on which prayers are pasted by Buddhist priests, who then put the wheel in rapid revolution. Each turn in supposed to have the efficacy of an oral repetition of all the prayers on the wheel. Sometimes it is moved by a stream.