Definition of "o'clock" []

• Of or according to the clock: three o'clock. (adverb)
• According to an imaginary clock dial with the observer at the center and 12 o'clock considered as straight ahead in horizontal position or straight up in vertical position. Used to indicate relative position: enemy planes at 10 o'clock. (adverb)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "'It must be -- eight o'clock' -- said the gasping voice -- '_eight o'clock_;' and the tone became a whisper, as though the idea thus half involuntarily revealed had been drawn jealously back into the strongholds of consciousness."
• "'It must be -- eight o'clock,' said the gasping voice -- '_eight o'clock_;' and the tone became a whisper, as though the idea thus half involuntarily revealed had been drawn jealously back into the strongholds of consciousness."
• "II. ii.324 (244,8) [Eleven o'clock] Ford should rather have said _ten o'clock_: the time was between ten and eleven; and his impatient suspicion was not likely to stay beyond the time."