Excusable
/ɪkˈskjuːzəbl/
Definition 1 of 1
Pro Tip 1/3Context Matters
Consider the situation to decide if something is excusable. Context like illness or accidents often validates the excuse. 
His absence from the meeting was excusable due to a family emergency.
Pro Tip 2/3Severity Levels
Not all mistakes are excusable. More serious ones might not be forgivable, even with good reasons. 
Cheating on the test is not excusable, unlike arriving late.
Pro Tip 3/3Temporary Acceptance
'Excusable' suggests a one-time forgiveness. It may not apply if the behavior repeats. 
Forgetting your homework once is excusable, but don't make it a habit.