Oxford Dictionaries defines terrorism as "the unlawful use of violence and intimidation, especially against civilians, in the pursuit of political aims."
US dictionary Merriam-Webster describes terrorism as "the systematic use of terror, especially as a means of coercion." There is, however, no commonly accepted definition. The term is often used in connection with unprovoked attacks and killings by an ideologically motivated group, like the so-called "Islamic State" (IS). But it is also sometimes used by governments to denounce opposition groups. This page collates DW content on terrorism.
British Airways has suspended flights to Cairo for seven days over what Britain's Foreign Office has called a "heightened risk of terrorism." Lufthansa has also temporarily canceled its flights to the Egyptian capital.