This example comes from a 16th century treatise printed in Poland.
It's known from a published transcription that it means 'quod'. The question is what is the last character of the abbreviation.
On the MUFI mailing list Peter S. Baker noticed correctly that this seems to be just a misprint of
This in turn is almost identical with an abbreviation of 'quod' noted in Capelli on p. 307:
I think you're asking for a Unicode glyph to represent the flourished d in the abbreviation.
The Unicode standard doesn't have one.
However, you might be able to approximate with Latin Small Letter D with Middle Tilde, ᵭ, if such a letter doesn't appear elsewhere in your text, or use a Combining horn d̛ although the placement may be too high by default.
[I've included these characters in this answer; your browser may not be able to display them correctly.]
Recently the needed glyph has became available in the JuniusX font as a stylistic variant of U+0111 LATIN SMALL LETTER D WITH STROKE (cv06). As the text in question does not contain U+0111 in its primary shape, the problem can be considered solved: the text can be encoded as plain text without the need to use some markup.
This is a scribal abbreviation.
The mark is a tilde.
When tilde is placed after an abbreviation, it just means to expand the word. So, for example:
qd~ = quod
q_~ = quam
The unicode symbol for a vertical tilde is 2E2F
There is no fixed standard for scribal abbreviations. One scribe might use q~ for qui, another for quam, another for -que, etc.
