Intel uses the letters to indicate the type of connection between the CPU and motherboard. So LGA = Land Grid Array [1]. The number is the number of pins/contacts connecting the CPU to the motherboard. So LGA1155 is a Land Grid Array Socket with 1,155 pins.
It's definitely not random, at least not with Intel. ARM is confusing as hell though. Part of the issue is that there is the ARM Instruction Set Architecture (ISA) that has different versions, and then there are different ARM CPU architectures, but those two don't necessarily need to correspond.
What do they gain from giving everything the most confusing names possible?
Sockets LGA1155, LGA1150, LGA1151. CPUs only differentiated by a jumble of digits anymore.
Something is seriously wrong with your product naming strategy when it needs to be clarified that ARM7 != ARMv7.