noun
neigh; whinny
The sound a horse makes; 'bray' is technically for donkeys, but may appear in some translations.
馬のいななきが遠くから聞こえた。
The neigh of a horse could be heard from afar.
いななく is the verb 'to neigh', while いななき is the noun form.
Derived from the verb いななく (to neigh). The exact origin of いななく is uncertain, but it is an old mimetic word for the sound a horse makes.