«وإن لم يبين تسمى القضية مهملة»
If the quantity of individuals is not specified, the proposition is called indefinite.
«الإنسان في خسر»
Humanity is in loss.
The subject “human” is universal and the judgment concerns its instances, but the expression does not explicitly use a quantifier like “every” or “some.” It is therefore indefinite (muhmalah) in this classification.
An indefinite proposition is not meaningless or false for that reason. It contains an assertion but leaves the quantity unexpressed.