"Full of zip" can be used to describe someone who is energetic, lively, and enthusiastic. Antonyms for this phrase include words that imply sluggishness, lethargy, and lack of enthusiasm such as slow, dull, and sluggish. Other antonyms include words that suggest tiredness, apathy, or boredom, such as weary, uninterested, and dispirited. Some other antonyms that can be used to describe someone who is not full of zip are gloomy, dreary, and lifeless. These words are the exact opposite of what "full of zip" represents and can be used when trying to convey a sense of tiredness, fatigue, or boredom.