An Etymological Dictionary of the German Language/Annotated/Hitze

by Friedrich Kluge

Hitze, feminine, ‘heat, ardour, passion,’ from the equivalent Middle High German hitze, Old High German hizza, feminine (for *hitja, the Gothic form); compare Dutch hitte, hette, Old Icelandic hite, masculine, ‘heat’; all formed by the weakest stage of gradation from the stem of the adjective heiß (Teutonic root hī̆t, hait, ‘hot’). Old High German hizza was adopted by Romance (compare Italian izza, ‘anger, indignation’).