Type III error, a type of incorrect inference in statistics.

Nitric oxide synthase 3, an enzyme

R-Type III: The Third Lightning, a video game

Motorola Type IIi Hybrid, a trunked radio system

The IBM Type-III Library, a distribution mechanism for unsupported IBM mainframe software such as CP/CMS

Type-III Civilization on the Kardashev scale, a way to classify civilizations