Held is a pair of separate status effects with the same name. You can be Held after being injured by some monsters; this effect simply holds you in place, preventing you from moving unless you manage to break the hold. It is similar to constriction, but without the damage over time.
Monsters who can hold you:
Getting Held occurs after you are struck with a throwing net, net trap, or web; this prevents you from moving or making most attacks until you manage to break loose. Blowguns and spells still function normally in this case.