User blog comment:PerhapsTheOtherOne/Speculative Spitballing: Goliath/@comment-4010415-20150608182803/@comment-7622429-20150608201339

Actually, that's not true, as far as I can tell. The translation for Kaiju is "strange beast". A monster. Any creature that fits the criteria of being a "strange beast" in Japan is considered a Kaiju, just like how all animation is considered anime.