1.
a. : the order of business appointed for an assembly for a given day : agenda
order of the day will include three conferences, rosary in common, confessions — Springfield (Massachusetts) Union
especially : the order of business appointed for a legislative body for a given day
the House … proceeded to the order of the day — Christopher Morley
b. : a stage of a bill or other matter that the House of Commons or other legislative body of the British Commonwealth has ordered to be taken under consideration on a particular day
2. : a statement issued by a commander to his troops usually in commemoration of some achievement
3. : the salient, characteristic, or dominant custom, theme, feature, or activity of a particular time : hallmark , keynote
lavishness is the order of the day — Betty Pepis
minuets, cancan, and ballet were the order of the day — New York Times
expansionism was the order of the new day — R.H.Brown