from The Century Dictionary and Cyclopedia
- n. The state or quality of being forbidding; repulsiveness, Richardson.
Sorry, no etymologies found.
There are a few stray "narrative" details -- the school is near a store "presided over by a matronly woman with a rather forbidding manner" -- but they are false leads: neither the matronliness, nor the forbiddingness, nor even the woman herself is ever mentioned again.
Unlike many of the gates of the rich, these were not ornamental—no fancy design, no family crest on the heavy bars, just thick double-welded iron in all its forbiddingness.
Aladdin frowned at Larch with all the forbiddingness that he could muster, but Larch was imperturbable.
You may have to try them many times; there is something of Nature's rudeness and forbiddingness, not only at the first, but probably always.