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. The definition for authoritarian is "favoring absolute obedience to authority.", the definition for corrosive is "Bitingly sarcastic.", and the definition for regale is "To amuse."

The definition for combustion is "Act of burning." Used in a sentence: Campers must use fire with great caution to prevent combustion of the parched brush. The definition for cunning is "showing clever insight.", the definition for placebo is "An inactive substance used in medical testing.", and the definition for implausible is "Unbelievable."

The definition for elate is "To fill with joy." Used in a sentence: It elated Margaret to be awarded first place in the science fair. The definition for eloquent is "fluent, expressive.", the definition for inflammatory is "Tending to excite anger.", and the definition for extant is "Currently existing."

The definition for turmoil is "Extreme confusion, agitation." Used in a sentence: The windstorm caused such turmoil in the lake that the sailboat capsized. The definition for scamper is "to run quickly.", the definition for conduit is "Means for transmitting or distributing.", and the definition for appraise is "To evaluate the worth of."

The definition for stern is "Harsh, severe." Used in a sentence: The stern principal canceled the prom after the seniors played a silly prank. The definition for diffident is "lacking self–confidence.", the definition for prune is "To reduce by removing excess.", and the definition for ecstatic is "Overwhelmingly emotional."