When I was a kid, a friend told me that a moment was officially 90 seconds.Bingo! That's what I was looking for; someone in my class told me that a moment is equal to 90 seconds. (I wanted to clarify if anyone had ever heard this before, but it seemed pretty unlikely to me to confine a moment to just 1 and a half minutes... !)
a. In medieval reckoning: the tenth part of a ‘point’ (POINT n.1 2c), i.e. the fortieth or the fiftieth part of an hour. Cf. MOMENTUM n. 1. Now hist.So: ninety seconds, 3 seconds, 1 second, and something on a geological timescale; and all but the last of those is cited as between 200 and 700 years old. The most recent cite for (a) is the year 1621, which undercuts somewhat the idea that that's what "a moment" means anything but a bar-bet or historical lexicography sense; and the whole section on moment-as-discrete-measure-of-time makes up all of one thirtieth of the whole entry on "moment".
b. In rabbinical reckoning (based on the lunar month): of an hour (3 seconds). Obs. rare.
c. A second. In later use only in moment-hand n. at Compounds. Obs.
d. Geol. A period of geological time corresponding to a stratigraphical zone (as defined by its fossil content).
posted by dowcrag at 2:34 AM on August 5, 2008