Gesture. WXYZ. Dictionary Devotee. Oxford University Press 2.0 Version 6th Edition. Gesture.
Oxford University Press
First, it means that someone uses his hand to show a special meaning to communicate with other people.
Second, it is usually mentioned as a part of gesture language.
--------- Yang Chen
This website tells us ten gestures we need to be careful to use.
Pictures of the gestures and ways to do the gestures
Different meanings in different situation and different countries
Reasons why need to beware those gestures