A manager who does a top-notch job for the company he works for, a top-notch university, top-notch services…all top-notch , excellent or a class apart…yes, that’s what the phrase top-notch means. And, when somebody says you are top-notch , then accept the compliment gracefully…they probably mean it…
A notch is a small cut or nick on a surface such as wood or metal. Notches have long been associated with measurements.
A possible origin of the phrase could be the following — If you are jumping hurdles, the height of the bar is usually determined by placing the bar into a notch. If the bar is raised to the top notch , that means the bar on the hurdle cannot go any higher.
The explanation is based on the idea that something higher in elevation is better than something that is lower. So something that‘s top–notch is considered high quality because it has reached a point where it can go no higher. So, just go ahead and believe it…you are top-notch !