The half-past-twelve sibling of the on-the-hour clock faces, part of the same rarely-precisely-used 24-piece clock set — most people reach for it as generic 'time' filler rather than to signal an exact 12:30. Some messaging apps auto-suggest the clock face matching the current time when you type ':clock', a fun bit of hidden functionality most users never discover.
Keywords: 12, 12:30, 30, clock, thirty, time, twelve, twelve-thirty