UEFI

UEFI is a technical acronym used primarily in computing and hardware engineering. It describes a modern standard for the software that initializes hardware during the boot process. In professional and technical discourse, it is treated as a singular entity representing a specification rather than a physical object.

Because it refers to a specific industry standard, it is almost always used as an uncountable noun. You would not refer to multiple "UEFIs" on a single motherboard; instead, you would discuss "UEFI settings," "UEFI firmware," or "UEFI mode" to specify different aspects of the interface.