Latin word ratio comes from Latin -tione, Latin reor (I reckon, calculate.. I think, deem, judge.)

Detailed word origin of ratio

Dictionary entry	Language	Definition
-tione	Latin (lat)
reor	Latin (lat)	I reckon, calculate.. I think, deem, judge.
ratio	Latin (lat)	Calculation, account. Manner, method. Reason, explanation.

Words with the same origin as ratio