Ventus is the incantation for a spell that causes a powerful wind (CG).
When the auror Stebbins was tailing Newt Scamander in London, Newt used this spell to impede and escape Stebbins. The wind was so strong that Stebbins was nearly knocked to the ground and his hat was blown away. Some Muggle passersby witnessed these effects of the spell; they were entertained although they could not understand what was going on (CG).
from "venti," Latin for "winds" and the term for the ancient Roman wind deities