rationale

The fundamental reasons for something; the basis.

The rational basis or motive of something; that which accounts for or explains the existence of something; reason for being.

A rational explanation or statement of reasons; an argumentative or theoretical account; a reasoned exposition.

Same as rational, 2.

An explanation or exposition of the principles of some opinion, action, hypothesis, phenomenon, or the like; also, the principles themselves.

an explanation of the basis or fundamental reasons for something

a justification or rationalization for something

a liturgical vestment worn by Christian bishops of various denominations

(law) an explanation of the fundamental reasons (especially an explanation of the working of some device in terms of laws of nature)