An ironclad oath is a solemn commitment to keep a promise or maintain secrecy. Synonyms for this expression include a solemn promise, a sworn pledge, and a vow of silence. These phrases evoke a sense of purpose and determination and are often used in legal and political contexts. Other synonyms for ironclad oath include a strong declaration, a solemn assurance, and a sworn statement. These expressions emphasize the gravity of the commitment being made and underscore the importance of keeping one's word. An ironclad oath is a serious undertaking, one that requires unwavering dedication to upholding the promise made.