The term 'proto suffix' refers to a prefix or suffix that is added to a word to create a new word. The crossword solutions for this term are 'plasm' (5 letters) and 'zoa' (3 letters). Plasm is derived from the Greek word 'PLASMA, ' which means 'something formed or molded.' It is often used in biology to refer to the living material of an organism, such as the protoplasm of a cell. Zoa is derived from the Greek word 'zoon, ' which means 'ANIMAL.' It is often used in biology to refer to a group of animals, such as the Protozoa, which are single-celled organisms.