Forethought is considering or planning something ahead of time. With some forethought, you can make sure to cook enough food for all the friends you invited to your dinner party.
People with forethought are good planners: it takes a little forethought to plan a trip to Europe or to make a monthly budget or to interview someone for a newspaper article. Instead of acting impulsively, using forethought means making a strategy or considering different outcomes before taking action. It comes from the obsolete forethink, "think of something beforehand," from Old English, foreþencan, "to premeditate or consider."