1. Of a liquid, to flow out of a container or over some barrier and into something or some place else. Don't fill the casserole dish too high, or some will spill over into the oven while it's cooking. The floodwaters rose above the embankment and spilled over into the adjacent fields.

2. To go beyond the borders or parameters of something and into something else, especially due to growing too large in size, amount, or scope. The protests outside the central bank began growing so large that they eventually spilled over into the entire financial district. So many people turned up to the bar for Mary's birthday that we all started spilling over into the streets. The stress I'd been feeling at work had started spilling over into other aspects of my life.