an advocate of rational egoism

(philosophy) The doctrine that it is rational to act in one's own self-interest. / (philosophy) A theory espoused by Ayn Rand, combining this doctrine with ethical egoism.

(slang, dated, World War I) A fussy or overly zealous military superior.

plural of ratio decidendi

(philosophy) A specific form of rationality focusing on the most efficient or cost-effective means to achieve a specific end, but not in itself reflecting on the value of that end.

Alternative form of K-ration

plural of K ration

Contrary to reason; lacking an appropriate or sufficient reason; irrational. / Lacking the ability to reason.

plural of rational function

(US, military) An individual canned, precooked, or prepared wet ration formerly issued to land forces in the US military.