to grow faint: to weaken and give way, in body or in spirit
Most often this verb describes strength draining away. In its plainest use it marks the physically weaker animals of a flock, the ones too feeble to keep up. But its home is Hebrew poetry, where again and again someone cries that their spirit or their very life faints, grows limp, or is overwhelmed inside them.
The picture is of the inner self going slack, as if wrapped up and muffled by grief, fear, or exhaustion. It is not a quiet tiredness but a collapse: children fainting in the streets for hunger, a soul giving way as trouble closes in. A close cousin (עָלַף) carries the same double life of wrapping and swooning, and the ordinary word for growing numb (פּוּג) sits nearby.
Because this spelling can also mean to wrap or cover, some scholars think the fainting sense grew out of that: to faint is to be enveloped, closed over by weakness.