There’s a knitting stitch combination that I’ve seen called a gather, and I’ve mostly seen it in Estonian stitch patterns, though I’m guessing they get used elsewhere too. Essentially, they are a combination of a double decrease (or more) and a double increase (or more) happening at the same time.
It sounds more complicated than it is. Take the 3/3 gather. When making a k3tog decrease, the basic principle is to insert the needle through all three stitches as if they were one stitch, and then knit one stitch in that clump of stitches. The gather expands upon that: knit those three stitches together without removing them from the needle, then yarnover, then knit the three stitches together again. This is the same as working a KYOK at the same time as a k3tog. Start with three stitches, end with three stitches, but they’re gathered together.
But thinking of it as a decrease/increase started making my brain fizz.