Calving

To give birth to a calf

To assist in a cow's giving birth to a calf

To give birth to (a calf)

(especially of an ice shelf, a glacier, an ice sheet, or even an iceberg) to shed a large piece, e.g. an iceberg or a smaller block of ice (coming off an iceberg)

"The glacier was starting to calve even as we watched."

The act of giving birth to a calf

The breaking away of a mass of ice from an iceberg, glacier etc.