diallel adjective 2noun 2forms 1 adjective2 •Involving crosses between several or all possible combinations.Nine varieties were chosen for a diallel crossing — 1970 •(rare) Of lines: Meeting and intersecting; not parallel.[…] like conditions and common ends as the ideal and goal of human effort are attained along parallel and not diallel lines in all the diversities of human application and invention. — 1900 noun2 •A set of all possible pairs of items from a specified set of items, especially when used for a study of diallel crosses.Pollinations in 1956 and 1957 produced seed for eight replications of all 78 combinations of a complete half diallel, excluding selfs. — 1978 •A form of logical fallacy in which a proposition that is required to prove another proposition can only be proved by means of assuming the truth of the proposition one is trying to prove; circular reasoning.This reminds us of what Sextus calls a diallel. A diallel is a situation where we need a in order to “prove” b and b in order to “prove” a (PH, I, 169), so that we can’t prove anything. — 2017 formsdiallels
