Entry 1 sense Webster, 1913 Ratiocination /(răsh`ĭ*ŏs"ĭ*nā"shŭn)/ · Ra·ti·oc·i·na·tion · IPA /ɹætiˌɑsiˈneɪʃn̩/ 01 n. The process of reasoning, or deducing conclusions from premises; deductive reasoning. 1. The process of reasoning, or deducing conclusions from premises; deductive reasoning.