futile
The definition for futile is "Without purpose, completely ineffective." Used in a sentence: Arguing with Andrew is futile because he never changes his mind.
inviolable
The definition for inviolable is "Secure from assault of trespass." Used in a sentence: Situated on a mountain, with sixteen–foot walls, the castle was inviolable.
periodic
The definition for periodic is "Occurring at regular intervals." Used in a sentence: The periodic innterruptions of the cuckoo clock prevented Li from concentrating.
prudent
The definition for prudent is "Marked by wisdom, shrewd." Used in a sentence: Manny was happy she followed Greg's prudent advice to study, as the test was difficult.
repentant
The definition for repentant is "Feeling regret." Used in a sentence: The repentant Dana admitted to cheating on the test.