Use 'inapplicable' when certain ideas or rules don't apply in a specific scenario. In space, Earth's gravity laws are inapplicable.
Pro Tip 2/3
Irrelevance Emphasis
'Inapplicable' often carries a stronger tone of irrelevance than just saying something is 'not relevant'. In discussions of ethics, one's wealth is inapplicable.
Pro Tip 3/3
Avoid Overuse
Using 'inapplicable' too often can make statements seem dismissive; use it judiciously. He referred to every suggestion as inapplicable, which stifled the brainstorming session.