An Etymological Dictionary of the German Language/Pforte
Pforte, f., ‘door, gate, portal,’ from the equiv. MidHG. pforte, OHG. (Franc.) pforta, f.; borrowed in the OHG. period, in the 8th cent., from Lat. porta; hence the absence of the permutation of t to z, which had been accomplished even in the 7th cent. (it is seen in OHG. pforzih, MidHG. pforzich, from Lat. porticus, which was introduced in the 5th or 6th cent. with the Southern art of building in stone; comp. AS. portič, E. porch). In MidG. and Lower Rhen., in which the permutation of t to z did not take place until later, we find in the MidHG. period the permutated form porze. ModHG. Porte, MidHG. porte, OHG. (UpG.) porta, is due to a more recent introduction into UpG.