The crossword solution for the term BOTH with the prefix PREF is AMBI. This prefix is derived from the Latin word 'ambi' which means 'BOTH'. It is used to refer to something that has two sides, or is shared by two people or groups. For example, an ambidextrous person is able to use BOTH hands equally well. Similarly, an ambivalent attitude is one that is characterized by having BOTH positive and negative feelings towards something.