beneficial
The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.
embellish
The definition for embellish is "To decorate." Used in a sentence: Sari embellished the plain curtains with satin ribbons and tassels.
interminable
The definition for interminable is "Never ending, or seemingly endless." Used in a sentence: The impatient Zoe found the longwinded lecture interminable.
oblivious
The definition for oblivious is "Lacking awareness." Used in a sentence: Love–struck Charlie was oblivious to everyone but the object of his affection.
retroactive
The definition for retroactive is "effective as of a prior time or condition." Used in a sentence: The retroactive law made even past infractions punishable.