Trifling matter is a term that can be used in different ways, depending on the context. It can be an instance when something is deemed unimportant, trivial, or insignificant. You can use a variety of synonyms to describe the same thing, including triviality, bagatelle, paltriness, insignificance, unimportance, frivolity, or pettiness. You might use these terms interchangeably, based on the message you want to convey. For example, the use of the term "triviality" might imply that something appears small in the grand scheme of things, while "pettiness" would suggest that something insignificant is beneath consideration due to its lack of value.