[ { "word": "Mellifluous", "definition": "Sweet or musical; pleasant to hear.", "example_sentence": "The mellifluous voice of the opera singer captivated the entire audience.", "antonym": "cacophonous", "tags": ["sound", "pleasant", "voice"], "difficulty": "medium", "suggested_review_interval_days": 7 }, { "word": "Ephemeral", "definition": "Lasting for a very short time.", "example_sentence": "The beauty of the cherry blossoms is ephemeral, lasting only a few weeks each spring.", "antonym": "permanent", "tags": ["time", "transient", "brief"], "difficulty": "medium", "suggested_review_interval_days": 3 }, { "word": "Pernicious", "definition": "Having a harmful effect, especially in a gradual or subtle way.", "example_sentence": "The pernicious rumors slowly eroded her reputation, even though they were untrue.", "antonym": "beneficial", "tags": ["harmful", "damaging", "subtle"], "difficulty": "hard", "suggested_review_interval_days": 14 }, { "word": "Capricious", "definition": "Given to sudden and unaccountable changes of mood or behavior.", "example_sentence": "Her capricious nature made it difficult to predict her reactions to unexpected news.", "antonym": "stable", "tags": ["unpredictable", "moody", "fickle"], "difficulty": "medium", "suggested_review_interval_days": 7 }, { "word": "Ubiquitous", "definition": "Present, appearing, or found everywhere.", "example_sentence": "In the digital age, smartphones have become ubiquitous.", "antonym": "rare", "tags": ["prevalence", "common"], "difficulty": "easy", "suggested_review_interval_days": 1 } ]