(n) (law) an explanation of the fundamental reasons (especially an explanation of the working of some device in terms of laws of nature), Syn. principle, Example:the rationale for capital punishment; the principles of internal-combustion engines
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
n. [ L. rationalis, neut. rationale. See Rational, a. ] An explanation or exposition of the principles of some opinion, action, hypothesis, phenomenon, or the like; also, the principles themselves. [ 1913 Webster ]