The habit or characteristic of doing things without delay.(noun)
The habit of adhering to a designated time.(noun)
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Use "promptness" in a sentence
"He recalled his promptness of resource and readiness for action."
""Well, sir, I feel that I owe you a great deal; perhaps more than I realize, as I recall your promptness on that memorable night of the storm.""
"Here, on the contrary, your volunteers "do their spiriting gently:" all is good-nature and good manners; and a front is diminished, or a column of companies in line of march is eased off to the right or left to make way for carts or coaches, as the case requires, with a promptness which is the more creditable from the fact that the execution of a change in movement is no light matter."