to infringe or trespass on someone or something; to move into the space belonging to someone or something. (Upon is formal and less commonly used than on.)I did not mean to encroach upon your property.I need lots of space. Don't encroach on me.
To advance or extend toward or into something beyond its proper or former limits: The weeds in my neighbor's yard are encroaching on my lawn. At the edge of the village, the desert encroaches upon grassland.