rationi
rationi is a Latin form of ratio, meaning “reason, account; method; plan”. It is the dative singular feminine noun.
Found 67 times in the Latin texts on Socratos.
Where it is used
Caesar, De Bello Gallico 1.40.9: Cui rationi contra homines barbaros atque imperitos locus fuisset, hac ne ipsum quidem sperare nostros exercitus capi posse.
All forms of ratio (declension table)
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Lewis & Short, A Latin Dictionary (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.