Design Nomenclature / Type
Font
Also called fount
The thing that renders a typeface — historically one size and one style of metal sorts in a case, now a file: Garamond Italic 10pt was a font, GaramondPremrPro-It.otf is a font. Digital fonts are software, which is why they are licensed rather than sold, and why a webfont's licence counts pageviews.
Not to be confused with
Origin
From French fonte, a casting — a font was literally what came out of the caster in one pour, hence one size, one style.