The phrase "pass up" means to miss or ignore an opportunity or to decline an offer. There are a few synonymous phrases that you can use instead of "pass up," including "turn down," "reject," "decline," "miss out on," or "overlook." To "turn down" an opportunity means to refuse an offer, while "reject" and "decline" both suggest a more final and deliberate decision to say no. "Miss out on" implies regret for not taking advantage of an opportunity, and "overlook" suggests that the opportunity was not recognized or noticed at the time. All of these phrases can be used in place of "pass up" to convey the idea of not taking advantage of an opportunity or offer.