When we talk about "spill out," we typically mean to let something flow over or out of its container, whether it's a liquid or something more abstract. However, there are a variety of synonyms that can be used in its place, depending on the context. For example, you might use "overflow" when talking about a container filled beyond capacity, or "trickle" when referring to a small amount of liquid seeping out. If you're talking about emotions or secrets, you might use "reveal" or "confide." And in the context of a busy schedule or packed itinerary, you might use "overspill" to indicate an overflowing amount of commitments.