"Become set" refers to the process of something becoming fixed, established, or firm. Some synonyms for this phrase include solidify, congeal, harden, settle, root, and establish. Solidify implies the process of something becoming cohesive and stable, while congeal suggests a thickening or coagulating process. Harden implies something becoming physically or mentally stronger, while settling suggests a process where water or sediment becomes deposited into a fixed position. Root or establish implies the process of something taking hold and becoming firmly established, such as a belief or tradition. All these synonyms capture the essence of something becoming set and fixed, whether physically, mentally or emotionally.