noun 1.Law.a.a crime, especially high treason, committed against the sovereign power.
b.an offense that violates the dignity of a ruler.
2.an attack on any custom, institution, belief, etc., held sacred or revered by numbers of people: Her speech against Mother's Day was criticized as lese majesty.
Origin:
1530–40; < French lèse-majesté, after Latin (crīmen) laesae mājestātis (the crime) of injured majesty