Attention-getter, in some rooms

• Town crier's cry
• When repeated, a court cry
• Courtroom attention-getter
• Town-crier's call
• Command from a bailiff
• When tripled, a court cry
• Hear ye!

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Oyez \O"yez`\ ([=o]"y[e^]s`; 277), interj. [Anglo-F. oyez hear ye. See Oyer .] Hear; attend; -- a term used by criers of courts to secure silence before making a proclamation. It is repeated three times. [Written also oyes .]

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
early 15c., from Anglo-French oyez "hear ye!" (late 13c., Old French oiez ), a cry uttered (usually thrice) to call attention, from Latin subjunctive audiatis , plural imperative of audire "to hear" (Anglo-French oier ; see audience ).