per·i·pe·te·ia also per·i·pe·ti·a 
(pĕr′ə-pə-tēə, -tīə)
(pĕr′ə-pə-tēə, -tīə)n.
A sudden change of events or reversal of circumstances, especially in a literary work.
[Greek, from peripiptein, peripet-, to change suddenly : peri-, peri- + piptein, to fall; see pet- in the Appendix of Indo-European roots.]