Araignée is the traditional name in France. Outside that tradition, butchers carry comparable beef cuts under different names — sometimes the same anatomical piece, sometimes a close cousin. The alternatives below are grouped by country so you can match what your local butcher actually carries.
Third member of the *morceaux du boucher* trio — all three (poire / merlan / araignée) are French-butchery boucher's-secret cuts traditionally kept by the butcher.
Both *morceaux du boucher* — small premium muscles on the round, traditionally kept by French butchers. Araignée is the spider-shaped muscle on the rear thigh; poire is the pear-shaped muscle on the inside thigh. Different muscles, same cultural-identity category.