"Toe the mark" is an idiomatic expression that means to conform to a standard or follow the rules. Antonyms for this phrase include resist, defy, rebel, challenge, and break free. These are actions that signify a refusal to conform to someone or something else's expectations. People may choose to resist or challenge rules because they disagree with them, or they may rebel against authority or convention. Breaking free of constraints or limitations is also an act of non-conformity, where people seek to create their rules and follow their path. Therefore, antonyms for "toe the mark" reflect an individual's need for self-expression and autonomy.