Where the expected stressed or unstressed syllable is switched for its opposite. Shakespeare frequently employed a trochaic inversion - i.e. by placing a trochee at the start of an iambic line.
[n] the act of turning inside out
[n] turning upside down; setting on end
[n] the reversal of the normal order of words
[n] (genetics) a kind of mutation in which the order of the genes in a section of a chromosome is reversed
[n] the layer of air near the earth is cooler than an overlying layer
[n] abnormal condition in which an organ is turned inward or inside out (as when the upper part of the uterus is pulled into the cervical canal after childbirth)