rationale
I
noun
account, basis, cause, elucidation, explanation, explication, exposition, fundamental reason, ground, logical reasoning, motivation, motive, presumption, proposition, reason, reasoning, speculation, surmise, theory
II
index
argument (pleading), basis, cause (reason), construction, explanation, ground, motive, reason (basis)
Burton's Legal Thesaurus.
William C. Burton.
2006