Reason VS Excuse

rea·son (r z n) n.
1. The basis or motive for an action, decision, or conviction.
2. A declaration made to explain or justify action, decision, or conviction
3. An underlying fact or cause that provides logical sense for a premise or occurrence
4. The capacity for logical, rational, and analytic thought; intelligence.

excuse ( k-sky s ) n.
1. An explanation offered to justify or obtain forgiveness.
2. An attempt to represent an offense as less serious than it appears by showing mitigating circumstances.

Oftentimes, we mistakenly use these two words in place of the other. Likely, on ocassions when we have forgotten to do something important and we have to come up with an explanation. But if you look at how each word is defined, you'll find a world of difference between them.

A "reason" to explain something requires logic and intelligence. An "excuse" implies coming up with a "lie" that, sometimes, do not make sense. There's a "poor excuse" but never a "poor reason". There are "acceptable reasons" but never "acceptable excuses".