illustration /ˌɪləsˈtɹeɪ̯ʃən/ noun5 •A picture designed to decorate a publication, or elucidate a literary work.The illustration showing the water cycle made it much easier to understand for the children.The sleeve of the band's new CD includes illustrations from deceased former members. •Something which illustrates; a comparison or example intended to make clear or apprehensible, or to remove obscurity. •The act of illustrating; the act of making clear and distinct. •The state of being illustrated, or of being made clear and distinct. •A calculated prevision of insurance premiums and returns (life insurance). formsillustrations