The crossword solution for the term 'PREFIX FOR 'CONSCIOUS'' is ECO, which is a three-letter prefix. ECO is derived from the Greek word oikos, meaning 'HOUSE' or 'HOME'. It is used to refer to environmental awareness and sustainability, and is commonly used as a prefix for words related to the environment, such as ecology, economics, and ecotourism. In this case, ECO is being used as a prefix for the word 'CONSCIOUS', which means having an awareness of one's own thoughts and feelings.