To grow beyond the normal or desired size, often covering or smothering something else. The weeds began to overgrow the garden, making it difficult to see the flowers.
To grow excessively or abnormally, often in reference to plants or cells. The doctor explained that the cells had started to overgrow, leading to the formation of a tumor.
To cover or spread over (a surface or object) by excessive growth. Ivy threatens to overgrow the old stone wall if it is not trimmed regularly.