When do you call someone lazy?
Probably when "they're not doing things they obviously should be doing, for no good reason at all."
But then, what does calling them lazy inform you about?
Slow down, re-read that, because it's important --
What does calling someone "lazy" inform you as to why it's happening, or possible solutions?
If you look closely at the word lazy, you'll notice it's just a synonym for what's already happening.
You see someone not doing things they should obviously be doing, for no good reason at all. So you call them lazy. But what's being lazy? It's "not doing things that obviously should be doing for no good reason at all..."
The reasoning is cyclical and circular. The word "lazy" becomes a label or judgment which is not particularly informative or actionable.
The more I think about and discuss this sort of thing with smart people, the more I realize two things --
(1) A staggeringly large amount of language are subtle cues to morality as opposed to actual explanations, and,
(2) Most of these quasi-moral labels are un-insightful and un-actionable.
Perhaps an alternative is to explain things as mechanically as possible.
Something like, "I see Joe isn't getting work done that really seems to me like it should be getting done for no good reason at all... hmm... I wonder if he's motivated and sees a reward? What's his momentum been like lately? Has he trained habits and work routines? Does he have exact clarity on what the final outcome that worthwhile is, why it matters to him, and what precisely the next step is? What's his peer group and reference group like? Has he ever trained in concentration and impulse control? Has he ever excelled at a high level in it? If yes, when and how did he fall off? What's his health, stamina, and fatigue levels like?"
And so on.
You might then wind up with an explanation like, "Joe seems lazy to me, but then, he's doing work that he doesn't really care about the payoff from it. Additionally, he never really trained in work habits, study skills, concentration, impulse control, or anything related to that. And it's normal among his coworkers to slack off and screw around, and the whole workplace has a culture of minimal accountability... I don't know what precisely a solution to better performance would be, but there's certainly some levers to pull here."
Of course -- this all applies to you too. Moral explanations tend to underperform mechanical explanations when you want to actually accomplish stuff.