The use of violence and threats to intimidate or coerce, especially for political purposes.
There are no conventional nor collectively agreed signs for terrorism. There are several signs, depending on the contexts.
One of some signs. [Video contributed by Peter Hershon, 2017.
One of some signs. [Video contributed by Elinor Goldberg, 2017.
Written ASL digit for "TERRORISM". Handshape "5" to "S" downward the face from forehead. Contributed by Adrean Clark in the ASLwrite community, 2017.