Older sister of Miranda Goshawk. Romilda enjoyed tricking her younger sister Miranda with inaccurate incantations. When Miranda published her famous spellbook, she had special editions created for her sisters with incorrect incantations in them. Romilda suffered a magical mishap as a result, but eventually her tail disappeared (BoS).
Romilda is probably from the Goshawk family.
Goshawk = Old English for a large, short-winged hawk once used in falconry.