The crossword solution for the term 'PREFIX WITH PRACTICE OR FUNCTION' is MAL, which is a three-letter prefix. MAL is derived from the Latin word malus, meaning bad or evil. It is used to form words that describe something as being bad or wrong, such as malfunction, malpractice, and malefactor. It can also be used to describe something that is not functioning properly, such as maladjusted or malfunctioning.