The term 'suffix with proto-' refers to a type of word formation in which a prefix is added to the beginning of a word, and a suffix is added to the end. The two crossword solutions for this term are PLASM (5 letters) and ZOA (3 letters). PLASM is a suffix that means 'FORM' or 'SHAPE, ' while ZOA is a suffix that means 'ANIMAL.' Both of these suffixes are derived from the Greek language and are used to FORM new words.