Technical debt is a bit of a squishy term, generally referring to technical choices and the long term consequences in code. You’ll need to pay that debt one day so the metaphor goes.
I admire Bill Clark’s calling:
I’m obsessed with tech debt. I want to find it, I want to understand it, and where possible, I want to fix it.
That’s from his 2018 article A Taxonomy of Tech Debt related to his work on League of Legends for Riot Games. Instead of being hand wavy about it though, he comes up with metrics for it to help understand and prioritize it. Impact: how annoying is it for both users and developers. Fix Cost: how much work is it going to be to deal with it. Contagion: how much worse is it going to get if you don’t deal with it. Love that last one.