المعنى الاصطلاحي

Wearing the garment over one's head or shoulders and letting its edges hang down on both sides, without lifting any of them, while wearing what covers one's "‘awrah" (what should be covered of the body).

الشرح المختصر

"Isdāl" (letting the garment hang down) is a way of dressing in which one lets his garment hang over the shoulders or the head without wearing it, by letting both edges of the garment hang on the right and left sides without holding them together or sliding one edge over its opposite shoulder; otherwise, it is not called "isdāl".

التعريف اللغوي المختصر

"Isdāl": letting hang down. It is derived from "sadl", which means letting something hang down from above and act as a cover. Other meanings: letting the garment hang over the shoulders; and it was said: wearing a garment over one's head and letting it hang over one's shoulders.