OZ meaning in Academic & Science ?

The ounce is the name of several different units of mass, weight or volume and is derived almost unchanged from the uncia, an Ancient Roman unit of measurement.

The avoirdupois ounce (approximately 28.35 g) is 1⁄16 of an avoirdupois pound; this is the United States customary and British imperial ounce. It is primarily used in the United States to measure packaged foods and food portions, postal items, areal density of fabric and paper, boxing gloves, and so on, but is sometimes used also elsewhere in the Anglosphere.

Although the avoirdupois ounce is the measure used for most purposes, the 'troy ounce' of a little over 31 grams is used for the mass of precious metals such as gold, silver, platinum, palladium, rhodium, etc.

The term 'ounce' is also used in other contexts:

Historically, a variety of different ounces measuring mass or volume were used in different jurisdictions by different trades and at different times in history.