a hunting net: the gear that closes on a catch, and so a picture of being taken with no way out.
This word comes out of the world of hunting and fishing. It names the equipment that does the catching rather than the chase itself: the mesh that drops over a bird or drags through the water and holds whatever ends up inside it. Ecclesiastes sets it beside the fowler's trap (פַּח) and makes the same point both times, that the creature never saw it coming.
Because a net is something one party sets for another, the Bible reaches for it whenever someone is caught in a situation they cannot get out of. Job says God has closed his net around him, which is the protest of a man who feels hunted rather than judged. Ecclesiastes describes a woman whose heart is nets and whose hands are chains, stacking this word next to the great sweeping net (חֵרֶם) to make the picture inescapable. Proverbs puts it in the hands of evildoers, where a wicked man eyes what their trapping brings in.
One shade is easy to lose. A word for the gear can slide over into a word for what the gear brings home, which is why the hard line in Proverbs 12:12 is translated "net" in some Bibles and "spoil" in others.