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So...it's not really italic, but some typefaces don't have a true italic. For these, to fill in where one wants an italic style, there may be simply a slant added to the regular typeface. The result of this is called an oblique. I guess you could call that "semi-italic" in a sense.
https://en.wikipedia.org/wiki/Oblique_type
Oblique type is a form of type that slants slightly to the right, used for the same purposes as italic type. Unlike italic type, however, it does not use different glyph shapes; it uses the same glyphs as roman type, except slanted. Oblique and italic type are technical terms to distinguish between the two ways of creating slanted font styles; oblique designs may be labelled italic by companies selling fonts or by computer programs. Oblique designs may also be called slanted or sloped roman styles.[1] Oblique fonts, as supplied by a font designer, may be simply slanted, but this is often not the case: many have slight corrections made to them to give curves more consistent widths, so they retain the proportions of counters and the thick-and-thin quality of strokes from the regular design.[2][3]
There are also some procedural font formats that can take inputs to set various values, and I imagine that one input could hypothetically morph to a variable degree between an italic and regular face.
https://en.wikipedia.org/wiki/Variable_font
A variable font (VF) is a font file that is able to store a continuous range of design variants. An entire typeface (font family) can be stored in such a file, with an infinite number of fonts available to be sampled.[2]
The variable font technology originated in Apple's TrueType GX font variations. The technology was adapted to OpenType as OpenType variable fonts (OTVF) in version 1.8 of the OpenType specification.[3][4][5] The technology was announced by Adobe, Apple, Google, and Microsoft in September 2016. Making such a feature standardized in OpenType paved the way for support in many software platforms.[3][6][7][8]
Variable fonts should not be confused with variable-width fonts. A variable font may be either variable-width or fixed-width.[9]
I don't personally know off-the-cuff of a font that specifically does a procedural regular/italic morph, though.
