To intrude gradually or stealthily upon the rights, property, or territory of another. The new construction project began to encroach on the neighboring parkland.
To advance beyond proper or former limits. The sea has started to encroach upon the coastline, eroding the land.
To intrude upon or consume (time, attention, or other intangible resources) in a way that reduces or limits them. I don’t want to encroach on your free time, so I’ll keep the meeting brief.