A raid is a military attack, especially a quick surprise attack. The word comes from the military but has spread out — police might raid a shady nightclub to find bad guys, or a babysitter might raid the refrigerator.
When an army launches a raid, you can say they raid, or attack abruptly. This verb can also be used to mean "search" or "enter unexpectedly," as when police officers raid a suspect's home or summer campers' raid a neighboring cabin. The military meaning is the oldest, and the word comes from the Scottish rade, "a riding" or "a journey," from the Old English rad, which is also the root of road.