camaraderie
The definition for camaraderie is "Spirit of friendship." Used in a sentence: The manager hoped the retreat would increase the camaraderie among the feuding workers.
cunning
The definition for cunning is "Showing clever insight." Used in a sentence: The general devised a cunning strategy to outfox the enemy.
fickle
The definition for fickle is "Lacking constancy, changeable." Used in a sentence: The fickle Senji had a new best friend every month.
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.
incumbent
The definition for incumbent is "Necessary as a duty or responsibility." Used in a sentence: It was incumbent on Jack to attend his father's retirement party.