The definition for periodic is "Occurring at regular intervals." Used in a sentence: The periodic innterruptions of the cuckoo clock prevented Li from concentrating. The definition for trove is "valuable collection.", the definition for polarize is "To break up into opposing groups.", and the definition for incumbent is "Necessary as a duty or responsibility."

The definition for raucous is "Noisy, rowdy." Used in a sentence: Serena, who preferred quiet conversation, left the rancous party. The definition for repentant is "feeling regret.", the definition for fickle is "Lacking constancy, changeable.", and the definition for defiant is "Showing bold resistance."

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 raspy is "rough, grating.", the definition for combative is "Eager to fight.", and the definition for liability is "A person or thing whose presence or behavior is likely to cause embarrassment or put one at a disadvantage."

The definition for gruff is "Rough or stern in manner or speech." Used in a sentence: Heidi's grandfather was gruff, barking stern orders and hardly smiling. The definition for extol is "to praise highly.", the definition for immoderate is "Beyond usual or proper limits.", and the definition for proximity is "Closeness."

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 onset is "beginning.", the definition for diffident is "Lacking self–confidence.", and the definition for appraise is "To evaluate the worth of."