Oyer and Terminer
(Courts of) are general gaol deliveries, held twice a year in every county. Oyer is French for to hear- i.e. hear in court or try; and terminer is French for to conclude. The words mean that the commissioners appointed are to hear and bring to an end all the cases in the county.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894