the electrical discharge that travels along a nerve fiber
"they demonstrated the transmission of impulses from the cortex to the hypothalamus"
A thrust; a push; a sudden force that impels.
"The powerful impulse of the water knocked the boat off course."
In plain English: An impulse is a sudden urge to do something without thinking about it first.
"I bought the candy on impulse without thinking about my diet first."
Usage: Use impulse to describe an immediate, often spontaneous urge or desire rather than a carefully planned decision. It is frequently confused with the verb form in phrases like "on impulse," which correctly indicates acting without forethought.
To impel; to incite.
"A sudden impulse made him run across the street without looking either way."
The word impulse comes from Middle French impulser and originally meant to push or drive something forward. It entered English with this sense of a sudden urge or force that moves someone to act.