Yes, it is a real word. For example: 'He was unwilling to complete the task given'.
He was unwilling to do as he was instructed.
Refusal
resisting; unwilling
unwilling to relent
loath
You get the word idle.
Unwilling, disagreeable, unprepared.
Averse.
loth
The word reluctant is an adjective. It means to be unwilling.
Afraid
Incredulous