unworthy
Not deserving something good or not good enough for it.
Unworthy means not deserving something good, or not having the qualities needed for a particular role or honor. When you feel unworthy of praise, you think you don't really deserve the compliments you're receiving. A knight might be judged unworthy of his title if he acts cowardly instead of brave.
The word often appears when someone measures themselves or others against a standard. A student might worry she's unworthy of a scholarship because other applicants have better grades. A friend might feel unworthy of forgiveness after breaking a promise. Sometimes people unfairly judge themselves as unworthy when they've actually done nothing wrong. They simply doubt their own value or abilities.
Unworthy can also describe something that fails to match what's expected. A book might be unworthy of its bestseller status if the story is poorly written. An excuse might be unworthy of belief if it's obviously false.
The opposite is worthy: deserving of something or measuring up to a standard.