glyph
An image used in the visual representation of characters; roughly speaking, how a character looks. A font is a set of glyphs.
In the simple case, for a given font (typeface and size), each character corresponds to a single glyph but this is not always the case, especially in a language with a large alphabet where one character may correspond to several glyphs or several characters to one glyph (a character encoding).
Usually used in reference to outline fonts, in particular TrueType.