hand waving

American  

Also hand-waving,

noun

1. insubstantial words, arguments, gestures, or actions used in an attempt to explain or persuade.

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Example Sentences

When the Atlantic, the Post and the Times announced their opposition, Hegseth replied with an emoji of a hand waving goodbye.

From Salon

When Wolves equalised, Monteiro was about to bring on striker Hwang Hee-chan, but after some hand waving in Pereira's direction, the decision was changed.

From BBC

Frustration then boiled over as animated hand waving was aimed the way of team-mate Rafael Leao late in the game.

From BBC

“Some people think that conducting is just a combination of hand waving and keeping the beat,” says Mr. Choi.

From NewsForKids.net

As the seconds go by, his apologetic demeanor morphs into something more like comedy — his head shaking, his hand waving in a vaguely Italian-style telegraph of exasperation, all of it coalescing into a fascinating improvisational bit.

From New York Times