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 euphoria is "feeling of great happiness.", the definition for stern is "Harsh, severe.", and the definition for pathos is "Sympathetic pity."

The definition for onset is "Beginning." Used in a sentence: Crocuses bloom at the onset of spring, sometimes even before the snow melts. The definition for commemorate is "to mark by a ceremony.", the definition for pretense is "False intention or purpose.", and the definition for curtail is "To make less."

The definition for diffident is "Lacking self–confidence." Used in a sentence: The diffident student never raised her hand in class, even when she knew the answer. The definition for corroborate is "to support with evidence.", the definition for melodious is "Having a pleasing melody.", and the definition for turmoil is "Extreme confusion, agitation."

The definition for avian is "Relating to birds." Used in a sentence: The old man affectionately referred to pigeons as his "avian friends." The definition for solace is "source of consolation.", the definition for dubious is "Questionable.", and the definition for precept is "A general rule of action."

The definition for liability is "A person or thing whose presence or behavior is likely to cause embarrassment or put one at a disadvantage." Used in a sentence: Kevin's growing fatigue was a liability as he attempted to climb the steep hill. The definition for egotist is "self–important person.", the definition for clarity is "Clearness.", and the definition for compulsion is "An irresistible impulse."