降下こうか Common Noun Irregular Intransitive English jmdict 1 noun (common) (futsuumeishi) noun or participle which takes the aux. verb suru intransitive verb descent;fall;drop;(atmospheric) depression その大型機は鋭い音を立ててほとんど直角に降下した。 The giant plane screamed down in an almost vertical dive. 2 noun (common) (futsuumeishi) noun or participle which takes the aux. verb suru intransitive verb passing down (of an order, decree, etc.)