To move from one side to another, especially by going over or through something. The deer crossed over the river to reach the other side.
To change from one activity or field to another. After years in finance, she decided to cross over into teaching.
To blend or merge different styles or genres, especially in music or entertainment. The band crossed over from rock to pop with their latest album.
To pass from one phase or condition to another. The project crossed over from planning to execution last month.