1) Bethink 2) Cogitate 3) Introspect 4) Invent 5) Meditate 6) Ponder 1) Cogitate 2) Contrive 3) Create by mental act 4) Create mentally 5) Devise 6) Forge 7) Formulate 8) Invent 9) Reflect deeply on a subject 10) Think out 11) Think through 12) To consider fully 13) To think out 
to discover by thinking out or reasoning
• (v. i.) To cogitate. • (v. t.) To think out; to find out or discover by thinking; to devise; to contrive.
Ex·cog'i·tate transitive verb [ imperfect & past participle Excogitated ; present participle & verbal noun . Excogitating .] [ Latin excogitatus , past participle of excogitare to excogitate; ex out + cogitare
to think out; devise; invent. · to study intently and carefully in order to grasp or comprehend fully.