beneficial
The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.
compulsion
The definition for compulsion is "An irresistible impulse." Used in a sentence: Tamar, a shoe fanatic, could not resist the compulsion to buy the shiny red boots.
inflammatory
The definition for inflammatory is "Tending to excite anger." Used in a sentence: Garth's inflammatory remarks at the party made Gwen furious.
onset
The definition for onset is "Beginning." Used in a sentence: Crocuses bloom at the onset of spring, sometimes even before the snow melts.
ploy
The definition for ploy is "A contrived plan." Used in a sentence: Sarah thought George's ploy of borrowing her notes was a cowardly way to ask her out.