Spur of the moment

On the spur of the moment means to act spontaneously without premeditation and dates from the early 19th century. The expression in fact revives an old archaic expression ‘on the spur’, which dates from the 16th century and means in great haste. Any expression containing the word spur, such as ‘spur on’, ‘spur to action’, ‘win one’s spurs’ all derive from horse riding and have remained popular since the 1500s. See also win one’s spurs.