Originally a spirit between the gods and men. In the New Testament a demon is the same as an evil spirit, which may be translated as "devil." It consequently means a malevolent, invisible being, which the pre-Christian word "demon" did not imply. (Etym. Latin daemon, evil spirit; Greek daim_n, a god, genius, spirit.)
” invisible being”
Demons are only invisible at low levels of consciousness. As you raise up, they become physical tangible beings. This is why the master stated that the weeds were planted “while we were asleep” in Matthew 13.