IPA: /ˌfoʊtəʊsɪnˈθɛtɪk/
KK: /ˌfoʊtəʊsɪnˈθɛtɪk/
Relating to the process by which green plants and some other organisms use sunlight to make food from carbon dioxide and water.
Plants are photosynthetic organisms that convert sunlight into energy.
Photosynthetic → It is formed from "photo-" (from Greek "phōs", meaning light) and "synthetic" (from Greek "synthesis", meaning putting together). The word "photosynthetic" refers to the process of putting together food using light, specifically in plants.
Think of 'light' ('photo-') being used to 'put together' ('synthetic') food in plants — that's what photosynthesis is all about.