Definition of "areal"

Areal density is often used as a technology growth-rate indicator for the hard disk drive industry. Areal density is defined as the product of the linear bits per inch (bpil, measured along the length of the tracks around the disk, multiplied by the number of tracks per inch (tpi), measured radially on the disk (see Figure 9.1).

2004, Scott Mueller, Upgrading and Repairing Laptops, page 307

It should be clear then, that BMD[Bone Mineral Density] measurements with DXA[Dual-energy X-ray Absorptiometry] are two-dimensional or areal measurements, whereas BMD measurements with QCT[Quantitative Computed Tomography] are three-dimensional or volumetric. Because DXA measurements are areal, bone size can affect the apparent BMD.

2009, Sydney Lou Bonnick, Bone Densitometry in Clinical Practice: Application and Interpretation, page 157

The areal sweep efficiency EA is defined as the fraction of the total flood pattern that is contacted by the displacing fluid.

2010, Tarek Ahmed, Reservoir Engineering Handbook, page 985