The term "incidental effect" refers to an unintended consequence resulting from an action or event. Synonyms for this term include subsidiary effect, secondary effect, by-product, unintended consequence, and collateral effect. These terms are often used interchangeably, depending on the context in which they are being used. It is important to note that incidental effects can be positive or negative in nature and can have varying degrees of impact. When considering the potential incidental effects of an action or event, it is necessary to take into account both the intended outcome as well as any unintended consequences that may arise.