Is it permissible for a woman to wear concealing clothing other than an abaya outside the house, such as a skirt and a hijab, provided that it does not reveal her attractions?

The dress of a woman is not required to be a specific abaya or jilbab, nor is it required to be a single piece. Rather, the condition is that it be modest, without adornment, and not attention-grabbing. If the required legal modesty is achieved, then there is no harm in the hijab (definition) being one piece or two. It should be noted that a skirt defines the size of a woman's waist, so loose, flowing garments should be worn over it to cover her and conceal the size of her limbs.