I'm not sure if that's darwin terminology, but calling a process that's blocking on io or in a tight loop "frozen" certainly isn't tradition in UNIX - you're much more likely to use hung or stuck. In linux specifically the term has a completely different meaning - "freezing" a process is intentional and involves putting the process into a cgroup and then removing all cpu shares to prevent it from executing - suspending the process and allowing for sleep/hibernation/etc.