the.com/applicability

means The degree to which something — a rule, method, or idea — actually fits and works in a given situation.

from Traces back to the Latin applicare, meaning 'to attach to' or 'to fold toward' — ad (toward) plus plicare (to fold). The same root that gives us 'apply' and 'pliable.' The '-ability' suffix tacks on the sense of capacity or fitness, so the word literally carries the idea of being foldable-onto-a-situation — whether something can be folded into real use, not just admired flat on the page.