Nonmagical items
Definition
Nonmagical items are items without the "magic" special property flag. The flag's status can be determined by either identifying the item or by means of the detect magic spell.
Nonmagical weapons can be further enhanced by the enchant weapon spell, the item will still be considered nonmagical.
Especially for weapons it is important to know if the item is magical or nonmagical since many run mobs have resistances or immunities to either the magic or nonmagic kind of damage. Set is an example of mob with immunity to magic.