Hadn't is a contraction for had not. Some synonyms for this word include had never, did not have, lacked, was minus, wasn't in possession of, was devoid of, must not have had, and had no. These terms are generally used interchangeably, depending on the context and the tense used. They can be essential for expressing negative sentiments, such as regret, denial, or refusal. Additionally, using synonyms can help the writer or speaker avoid repetition and create a more diverse and engaging dialogue. Overall, there are many ways to express the idea of having not done or possessed something, and utilizing different synonyms can add depth and complexity to the language used.