Dictionary.net

a natural and unavoidable catastrophe that interrupts the expected course of events; "he discovered that his house was not insured against acts of God"

a natural and unavoidable catastrophe that interrupts the expected course of events; "he discovered that his house was not insured against acts of God"

Fr. In the law of insurance. Superior or irresistible force. Emerig. Tr. des Ass. c. 12.

Irresistible compulsion, coercion diplomatically recognized as irresistible. [French]

(Also) strike, war, act of God, &c., excusing fulfilment of contract.

[Fr.] is used as = a power against which one can do nothing. Sauf les cas de F. M., except in the case of impossibilities. Se Vis major; Forlorn hope.