What does vīs maior mean in Latin?

vīs maior, a noun, means “vis major (greater force; an act of God; an unavoidable accident)”.

What is the genitive of vīs maior?

The genitive singular is vīs maiōris. vīs maior is irregular, third declension.

nounirregular, third declension

vīs maior f (genitive vīs maiōris)

declension
form	singular	plural
nominative	vīs maior	vīrēs maiōrēs
genitive	vīs maiōris	vīrium maiōrum
dative	vī maiōrī	vīribus maiōribus
accusative	vim maiōrem	vīrēs maiōrēs vīrēs maiōrīs, vīrīs maiōrēs, vīrīs maiōrīs
ablative	vī maiōre vī maiōrī	vīribus maiōribus
vocative	vīs maior	vīrēs maiōrēs