The term PREFIX FOR 'AMOROUS' is solved by the word POLY, which is a four-letter prefix. POLY is derived from the Greek word 'polys' meaning 'MANY' or 'MUCH'. It is used to describe something that has MANY parts or aspects, and is often used as a prefix for words related to love and relationships. In this case, it is used as a prefix for the word 'AMOROUS', which means 'showing strong feelings of love or passion'. Therefore, the answer to the crossword clue is POLY, which is a prefix for the word 'AMOROUS'.