The r rotunda ⟨ ꝛ ⟩, "rounded r", is a historical calligraphic variant of the minuscule (lowercase) letter Latin r used in full script-like typefaces, especially blackletters.
The shape of the letter used in blackletter scripts Textualis as well as Rotunda is reminiscent of "half an r", namely, the right side of the Roman capital ⟨R⟩; it also looks similar to an Arabic numeral ⟨2⟩.
Like minuscules in general, this shape for r originated in the style of cursive writing that was common during the medieval period, which ultimately derived from scribal practice during Late Antiquity.
The r rotunda shape of cursive ⟨r⟩ resembling the numeral ⟨2⟩ is also found in a number of medieval scribal abbreviations containing ⟨r⟩, for example in the signs for the Latin word-final syllables ram, -orum and -arum.
Among them is the abbreviation for the syllable rum, consisting of a r rotunda with a cut, resulting in a shape very similar to the astrological symbol for Jupiter ⟨♃⟩.