continual vs cyclic

continual

adj
  • Recurring in steady, rapid succession. 

  • Seemingly continuous; appearing to have no end or interruption. 

  • Forming a continuous series. 

cyclic

adj
  • Characterized by, or moving in cycles, or happening at regular intervals. 

  • Firing at its full cyclic rate. 

  • Having chains of atoms arranged in a ring. 

  • Having parts arranged in a whorl. 

  • Being generated by only one element. 

  • Able to be inscribed in a circle. 

noun
  • The flight control used to control a helicopter's direction and rate of horizontal movement by tilting the lift vector of the helicopter's main rotor disk. 

How often have the words continual and cyclic occurred in a corpus of books? (source: Google Ngram Viewer )