A ḥāl (حال) describes the state accompanying the action of its possessor (صاحب الحال). A transient ḥāl (الحال المنتقلة) denotes a circumstance associated with the event rather than a permanent defining property. The source treats the original form of ḥāl as without wāw because it functions as a description of its possessor.
Example: “Jāʾa Zaydun ḍāḥikan” — Zayd came laughing. The single word “ḍāḥikan” is a circumstantial accusative, not a fully independent assertion.
When the circumstance is expressed by a complete clause, its independent sentence structure makes a link back to the possessor particularly important. This leads to the rules of circumstantial wāw and pronouns.