I wrote before that we have no Extraterrestrials here but people talking about ET.
This process of words becoming entities is clearly put by John Stuart Mill:
" The tendency has always be strong to believe that whatever receives a name must be an entity or being, having an independent existence of its own; and if no real entity answering to the name could be found, men did not for that reason suppose that none existed, but imagine that it was something peculiar, abstruse and mysterious, to high to be an object of sense."