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 fragile is "delicate.", the definition for distortion is "The act of twisting out of shape.", and the definition for iridescent is "Having a lustrous or attractivve quality."

The definition for revoke is "To cancel by taking back." Used in a sentence: After Kal's father revoked his allowance, he had no money for the movies. The definition for trove is "valuable collection.", the definition for grandiose is "With an affectation of grandeur.", and the definition for intricate is "Having complex and interrelated parts."

The definition for perception is "Capacity for seeing or understanding." Used in a sentence: His incredible perception made him the best detective on the force. The definition for commemorate is "to mark by a ceremony.", the definition for incongruous is "Not harmonious, incompatible.", and the definition for pretense is "False intention or purpose."

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 disconcert is "to throw into confusion.", the definition for appalling is "Inspiring dismay or disgust.", and the definition for condone is "To treat as acceptable."

The definition for untenable is "Not able to be defended." Used in a sentence: Rashid made the untenable statement that George Washington was the second president of the United States. The definition for salvage is "to save from ruin.", the definition for commemorate is "To mark by a ceremony.", and the definition for manifest is "Obvious."