1) Become firm 2) Become settled 3) Become solid 4) Cause to solidify 5) Change integrity 6) Coagulate 7) Congeal 8) Consolidate 9) Convert into a solid body 10) Freeze 11) French word used in English 12) Make solid or more solid 13) To become solid 14) To concentrate 15) To freeze, set 16) To make solid Found on https://www.crosswordclues.com/clue/solidify
So·lid'i·fy transitive verb [ imperfect & past participle Solidified ; present participle & verbal noun Solidifying .] [ Solid + -fy : confer French solidifier .] To make solid or compact. « Every machine is... Found on http://www.encyclo.co.uk/webster/S/141