allegory (n.)

Proto-Indo-European root meaning "beyond."

It forms all or part of: adulteration; adultery; alias; alibi; alien; alienate; alienation; allegory; allele;  allergy; allo-; allopathy; allotropy; Alsace; alter; altercation; alternate; alternative; altruism; eldritch; else; hidalgo; inter alia; other; outrage; outrageous; outre; parallax; parallel; subaltern; synallagmatic; ulterior; ultimate; ultra-.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit anya "other, different," arana- "foreign;" Avestan anya-, Armenian ail "another;" Greek allos "other, different, strange;" Latin alius "another, other, different," alter "the other (of two)," ultra "beyond, on the other side;" Gothic aljis "other," Old English elles "otherwise, else," German ander "other."

1590s, "open assembly place, chief public square and marketplace of a town; popular political assembly held in such a place," from Greek agora "an assembly of the People" (as opposed to a council of Chiefs); "the place of assembly; a marketplace" (the typical spot for such an assembly), from ageirein "to assemble," from PIE root *ger- "to gather." The Greek word also could mean "public speaking," and "things to be sold." For sense, compare Roman forum.