in ‧ ver ‧ sion /ɪnˈvɜːʃ ə n $ -ˈvɜːrʒ ə n/ BrE AmE noun [uncountable and countable]
1 . formal the act of changing something so that it is the opposite of what it was before, or of turning something upside down (=the bottom is on the top and the top is on the bottom)
2 . technical a type of weather condition in which the air nearest the ground is cooler than the air above it