The degree to which a thing is applicable; relevancy(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "applicability" in a sentence
"It remains valid science even though its range of applicability is limited."
"A few hold promise (e.g., wind) but the scale of their applicability is questionable."
"Insulation is a meaningful answer for new construction but for existing buildings this is quite limited in applicability since much that could be imagined turns out to be quite cost prohibitive."