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1640s, originally astrological, of planetary alignments, from Latin, literally "five twelfths" (especially "five unciae," that is, "five-twelfths of an as," the basic unit of Roman currency), from quinque "five" (see quinque-) + uncia "ounce; a twelfth part (of anything)," related to unus "one" (see one). Applied, especially in garden design, to arrangements like the five pips on a playing card (1660s). Related: Quincuncial.