Antonyms for the phrase "good as one's word" include unreliable, untrustworthy, dishonest, and deceitful. When someone is not good as their word, it means they have a habit of breaking promises or not following through on commitments. People who lack integrity may use empty words to manipulate or deceive others, leading to broken relationships and a loss of trust. Therefore, it's important to be good as one's word as it helps people build strong bonds that last long. Otherwise, words become meaningless, and relationships become fragile. In conclusion, being good as one's word is essential to establish credibility, trustworthiness, and reliability in personal and professional lives.