1. at or past the point when something should have happened
it's about time you got here!
This expression is most commonly used in a social situation, and emphasizes that something should happen soon or should have happened a long time ago. There is a key difference in how those two variations are delivered in speech. If you are using 'about time' to say that something should happen soon, you would usually say it in a neutral tone of voice. If, however, you are saying that something should have happened a long time ago, the tone is often one of impatience, anger or excitement. An alternative expression is 'it's high time.'