The term LB. OR OZ. is an abbreviation for two different units of measurement. The abbreviation LB. stands for the unit of measurement known as the pound, while OZ. stands for the unit of measurement known as the ounce. The pound is a unit of mass or weight in the imperial system of measurement, while the ounce is a unit of mass or weight in the United States customary system of measurement. The abbreviation AMT (3 letters) stands for the word amount, which is used to refer to the quantity of something. The abbreviation WGT (3 letters) stands for the word weight, which is used to refer to the heaviness of an object.