The term 'Fill a Suitcase' can be solved by the four-letter word 'PACK'. This term is used to describe the action of putting items into a suitcase in order to prepare for a journey. It involves selecting the items that are necessary for the trip, and then arranging them in the suitcase in an organized manner. Packing a suitcase is an important part of the travel process, as it ensures that all the necessary items are taken on the journey.