The term 'prefix with -derm' refers to three words: endo-, ENTO-, and ecto-. Endo- is a prefix meaning 'WITHIN, ' ENTO- is a prefix meaning 'INSECT, ' and ecto- is a prefix meaning 'OUTSIDE.' These prefixes are often used in medical terminology to refer to different parts of the body, such as endoderm, entoderm, and ectoderm. Endoderm refers to the innermost layer of cells in an embryo, entoderm refers to the middle layer of cells in an embryo, and ectoderm refers to the outermost layer of cells in an embryo.