(lack of) natural ability or skill
inaptitude - inability
If you have a talent for doing something, whether innate or learned, it can be said that you have an ‘aptitude’ for it. This is something very positive and a great indicator of success in whatever field your ability lies. An ‘inaptitude’, on the other hand, is a lack of ability or skill. Unsurprisingly, this hindrance only leads to negative outcomes.
Tom undoubtedly worked hard, but his inaptitude meant that the management role was simply too much for him. That’s why he was demoted.
I was nervous about starting my first teaching job, but I was delighted to discover that I seem to have a natural aptitude for it.
The tests we set job candidates are not aptitudinal. Instead, they focus more on personality traits.