The act, process, or cost of fitting; or fixtures and fittings collectively.
From 'fit' plus the suffix '-age' (act, process, or collection of), creating a noun. The '-age' suffix often creates abstract nouns for processes or collections, as in 'baggage' or 'passage.'
Old invoices from tailors and builders mention 'fittage costs' as a separate line item—it's a wonderfully economical word that bundles the entire process of fitting into one professional term.
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