Glyph

A glyph is an element of writing. Example: the ligature æ in archæology represents a and e letters.
More exactly, a glyph is an element in an agreed set of symbols. A mark used in a language is a glyph, but in another language it may not be a glyph. For example, an n with tilde, ñ, is used in Spanish, as in piñata. It is not a glyph in English.