one o'clock

noun4

1. •
   The start of the second hour of the day; 1:00 a.m. (01:00).

   • The bar closes at one o'clock (= "The bar closes at 1:00 a.m.").
2. •
   The start of the fourteenth hour of the day; 1:00 p.m. (13:00).

   • The next train comes at one o'clock (= "The next train comes at 13:00").
3. •
   (informal) A position ahead and slightly rightward (horizontal clock orientation) or almost directly above (vertical clock orientation) (from the location of the 1 mark on a clock face)

   • We've got a bogey at one o'clock.
4. •
   (informal) A dandelion.