solidify
v. C1 Advanced US //səˈɫɪdəˌfaɪ// UK //səlˈɪdɪfˌaɪ// so·lid·i·fy
v. to become hard and firm, or to make something more certain and permanent. You use this when a liquid turns into a solid or when an idea becomes a real plan.
v. to change from a liquid to a solid state; to make something more permanent, stable, or certain. Often describes the transition of physical matter or the consolidation of abstract concepts.
The liquid begins to solidify as it cools down.
The new government needs to solidify its power by passing several important laws in the first year.
As the negotiations progressed, the initial agreement began to solidify into a formal treaty that both nations could sign without hesitation.
From French solidifier. By surface analysis, solid + -ify.