science of time, 1752, a modern word coined from Greek hora "hour; part of the day; any period of time" (see hour) + -logy. "The term horology is at present more particularly confined to the principles upon which the art of making clocks and watches is established" [American edition of the "British Encyclopedia," Philadelphia, 1819]. Earlier in English it meant "clock, clock dial" (c. 1500), in which sense it represents Latin horologium "instrument for telling the hour" (in Medieval Latin, "a clock"), from Greek horologion "instrument for telling the hour" (a sundial, water-clock, etc.), from horologos "telling the hour." Related: Horologist (1795); horological (1590s). Horologiography (1630s) is the art or study of watches and timepieces.