'brick' in general is a sliding scale based on how many device debug/recovery tools you have access to and how much device disassembly you're willing to tolerate.
No, iOS devices can also soft-brick, it's just a general term. Most often people encounter the term in relation to hacking/rooting hardware, like a Nintendo DS/Switch for instance. Hitting up Wikipedia or Trends can help you dig through its usage considering how Google's search algo heavily biases current events wrt relevance.
