It's so rare these days I really don't understand why people fuss over the definition.
It's almost impossible to brick anything with software, and even in hardware unless you damage the PCB itself you can usually recover if you tried hard enough (e.g. Even if you fry a $1500 FPGA you could technically reflow a new one and pray the bitstream is OK if you need it fixed now - although I'd rather you than me)
Technically you could also lay out new components and copper trace on an actual brick, too.
I've always understood it to mean 'broken beyond software or high-level firmware repair'. i.e. if not actually a blown component, something needs to be reflashed which has an inaccessible JTAG header or something, rather than something 'higher level' like recovery images over ADB & USB.
It's almost impossible to brick anything with software, and even in hardware unless you damage the PCB itself you can usually recover if you tried hard enough (e.g. Even if you fry a $1500 FPGA you could technically reflow a new one and pray the bitstream is OK if you need it fixed now - although I'd rather you than me)