climacophobia
The fear of staircases or of falling down stairs.
uncountable
Lucy: Are you afraid of staircases? If you are, then you have climacophobia.
Where it comes from
From Ancient Greek κλῖμαξ (klîmax, “ladder, staircase”) + New Latin -phobia, from Ancient Greek φόβος (phóbos, “fear”).
Adapted from the Wiktionary entry climacophobia (CC BY-SA 4.0).