amenazadores

adj. menacing, threatening; ominous; angry

= ominous, threatening, frowning, forbidding, looming, scary [scarier -comp., scariest -sup.], menacing.
Ex: At first blush, nothing seemed particularly ominous about the formation of the ad hoc committee.
Ex: It is easy to become carried away by the sheer size of the so-called 'information explosion' and to regard the growth of literature as a phenomenon as threatening to civilization as a virulent epidemic or the 'population explosion' in the third world.
Ex: The impulse to learn is a ruling passion in very few people; in most of us it is so weak that a frowning aspect can discourage it.
Ex: All those shelves full of books are forbidding, daunting.
Ex: The automated catalogue became a spectre of looming change because the same electronic advances that made the online catalogue a reality promised even greater transformations = El catálogo automatizado se convirtió en un espectro del inminente cambio ya que los mismos avances electrónicos que hicieron realidad el catálogo en línea prometían transformaciones aún mayores.
Ex: The very term 'outsourcing' is seen by many cataloguing departments as a scary word.
Ex: This is a collection of articles on the theme: Books for children with murderous, shocking, menacing endings.
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* avecinarse de un modo amenazador = loom + large on the horizon.
* conducta amenazadora = threatening behaviour.