When we say "let it go by," we usually mean to not pay attention to something or to not let something affect us. There are several synonyms for this phrase that can be used in different contexts. For example, "overlook" means to disregard or ignore something, while "dismiss" means to reject or disregard something as unworthy of consideration. "Ignore" is another synonym that means to pay no attention to something, and "shrug off" means to dismiss as unimportant or insignificant. Other synonyms include "brush aside," "discount," "disregard," and "let pass." No matter which synonym you choose, they all convey the same message of not getting affected by something.