Since you're posting in the barbell forum I would say this could be oriented a few ways: general strength, powerlifting-specific (squat/bench/deadlift 1RMs), and weightlifting/Olympic Lifting.
For Olympic Lifting, here is one way:
Olympic Weightlifting Skill Levels Chart
Unfortunately he doesn't have a corresponding chart for masters.
So these are weight class and weight totals, but there is also a helpful description in each Level relative to technical proficiency, etc.
Powerlifting probably has similar charts to see if you're competitive in your weight class.
For general strength development, I agree with
@Blake Nelson @jef and
@Kettlebelephant that it's defined by how you respond to training. If you get stronger every session, you're a beginner (or novice). This can last many months. And, it's lift-specific. You can be a beginner in the squat and be intermediate in the deadlift, for instance. If you get stronger week to week on a dedicated program, you're intermediate. And if you have to do fancy cycles and programming tricks and peaking and all sorts of supplemental lifts and other things to add to your 1RMs, you're advanced.
The funny thing is that people follow intermediate programs like 5/3/1 and advanced programs found in all sorts of publications when they are a beginner and very simple programming would work just fine, and
actually would work even better. MOST OF US ARE BEGINNERS. Either because we never developed our strength with a dedicated strength training program, or because we haven't maintained it. But, being a beginner/novice is good news. It means strength can be build relatively quickly and without a lot of complexity. You just have to do the work.