A stupid, clumsy mistake
To move awkwardly or clumsily
To proceed or perform in an unsteady, faltering manner
To harm irreparably through inept handling; make a mess
It is difficult to suppose that such a blunder was not preconcerted.
The blunder was soon committed.
A burst of childish laughter greets my blunder, and the pantomime begins all over again.
This tactical blunder cost him his popularity and materially assisted the secret operations of the king.
Unfortunately his successor, Louis VII., almost destroyed his work by a colossal blunder, although circumstances seemed much in his favor.