Word Study
ratiocinate
CIDE DICTIONARY
ratiocinate, v. i. [L. ratiocinatus, p. p. of ratiocinari, fr. ratio reason. See Ratio.].
To reason, esp. deductively; to offer reason or argument. [1913 Webster]
OXFORD DICTIONARY
ratiocinate, v.intr. literary go through logical processes, reason, esp. using syllogisms.
Derivative
ratiocination n. ratiocinative adj. ratiocinator n.
Etymology
L ratiocinari (as RATIO)
For further exploring for "ratiocinate" in Webster Dictionary Online