REAR'%3B SUSTAIN (5 letters) 'SUPPORT' The term 'REAR' is a four-letter word that means the BACK or hindmost part of something, while 'SUPPORT' is a five-letter word that means to SUSTAIN or hold up. Together, these two words can be used to describe the act of providing assistance or backing to someone or something. This could include physical SUPPORT, such as holding up a wall, or emotional SUPPORT, such as providing encouragement and understanding.