The story
Initialism of Intel Architecture, 64-bit.
Etymology from Wiktionary, CC BY-SA 4.0.
IA-64
Today it means: An EPIC 64-bit instruction set architecture designed to allow relatively simple, cheap CPUs to execute many 64-bit instructions simultaneously and with potentially very high performance; developed by Intel in the late 1990s with the intent of replacing the older x86 architecture, but was delayed and proved uncompetitive with x86 (especially x86-64), seeing use only in Intel's own Itanium line of high-end CPUs. Full definition →