Noun
usermode (uncountable)
(computing, often attributive) A level of privilege on a system allowing users to run programs etc. safely without full access to the operating system.
A key component of a microkernel is a good IPC system and virtual-memory-manager design that allows implementing page-fault handling and swapping in usermode servers in a safe way. Source: Internet
Since all services are performed by usermode programs, efficient means of communication between programs are essential, far more so than in monolithic kernels. Source: Internet