beneficial
The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.
epistolary
The definition for epistolary is "Contained or carried on in letters." Used in a sentence: The shoebox filled with letters was the ony remains of Ming's epistolary friendship with Emile.
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.
pomp
The definition for pomp is "Showy display." Used in a sentence: Jan couldn't help enjoying the pomp of the elaborate wedding ceremony.
precept
The definition for precept is "A general rule of action." Used in a sentence: All the students know Mrs. Brown's strict precept; no talking in class.