Английский Этимологический словарь - second (n.)

- "one-sixtieth of a minute," 1391, from O.Fr. seconde, from M.L. secunda, short for secunda pars minuta "second diminished part," the result of the second division of the hour by sixty (the first being the "prime minute," now called the minute), from L. secunda, fem. of secundus (see second (1)). Shortened form sec first recorded 1860.