Excusement is a slightly archaic term that can be replaced by several other words that convey similar meanings. One fitting synonym is "pretext", which refers to an excuse made up to hide the true reason behind an action or event. Alternatively, "justification" can be employed when seeking to explain or defend a particular decision or behavior. "Alibi" is another suitable substitute, particularly when discussing someone's claimed absence or non-involvement in an alleged wrongdoing. "Rationale" can be used to describe the underlying reasoning behind an action, while "defense" and "explanation" can also resonate as synonyms for excusement. It is important to consider these alternatives to refine one's writing or speech and avoid repetition or monotony.