- of, by, or according to the clock (used in specifying the hour of the day): It is now 4 o'clock.
- according to a method for indicating relative position whereby a plane in space is considered to be numbered as a clock's face, with 12 o'clock considered as directly ahead in horizontal position or straight up in vertical position.
Origin of o'clock
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for o'clock
It was getting on for three o-clock now, and the quality were beginning to arrive.The Elusive Pimpernel
Baroness Emmuska Orczy
The governor threatened him with death to-morrow by ten o-clock.Biographia Scoticana (Scots Worthies)
By four o-clock it was growing dark, and Mrs. Levice became restless.Other Things Being Equal
- used after a number from one to twelve to indicate the hour of the day or night
- used after a number to indicate direction or position relative to the observer, twelve o'clock being directly ahead or overhead and other positions being obtained by comparisons with a clock face
C18: abbreviation for of the clock
Word Origin and History for o'clock
c.1720, abbreviation of of the clock (1640s), from Middle English of the clokke (late 14c.). Use of clock hand positions to describe vector directions or angles is from late 18c.
Online Etymology Dictionary, © 2010 Douglas Harper