(In both the 12-hour clock and the 24-hour clock) The start of the eleventh hour of the day; 10:00 a.m. (10:00).

(In both the 12-hour clock and the 24-hour clock) The start of the seventh hour of the day; 6:00 a.m. (06:00).

(US, especially black slang, of a woman) Straight up and down, without curves, like the hands of a clock.

Alternative form of four o'clock

(In both the 12-hour clock and the 24-hour clock) The start of the tenth hour of the day; 9:00 a.m. (09:00).

(slang, humorous) The time of the first beer (or alcoholic beverage) of the day. / (slang, humorous) Time for a beer (the first of the day or otherwise).

(slang, humorous) The time of the first glass of wine (or alcoholic beverage) of the day.

(informal, humorous) A time of day, usually during the night or early in the morning, considered unreasonable or when one is prone to poor judgment.

plural of four-o'clock

plural of twelve o'clock