When we need to express that we have successfully achieved or finalised something, we often use the phrase "nail it down." However, there are several synonyms for this commonly used expression. One such phrase is "pin it down," which means to clarify a situation or make a definitive decision. Another similar expression is "put the finishing touches on," which implies that all the necessary components of a project have been completed. Similarly, "dot the i's and cross the t's" means that all details have been addressed. Lastly, "seal the deal" suggests that a firm agreement has been made, and all parties involved are content with the outcome.