An Etymological Dictionary of the German Language/Pfingsten
Pfingsten, plur., ‘Whitsuntide,’ from MidHG. pfingsten, which in form is really a dat. plur. (comp. Mitternacht), and was used at an early period for all cases; OHG. zi *pfingustin, ‘Whitsuntide,’ is by chance not recorded (Notker uses a pedantic semi-version, zi finfchustin). Formed from Lat. and Gr. πεντεκοστή (Ital. pentecoste, Fr. pentecôte), lit. ‘fiftieth day after Easter’; OSax. te pincoston, ‘at Whitsuntide,’ Du. pinksteren, as well as OSlov. pętikostij, Whitsuntide.’ While the term Ostern, applied to the Christian passover, was orig. a heathen word, which has been retained in E. and G., in this instance the ecclesiastical name obtained on the Continent, and that probably prior to the OHG. period, as the initial pf in MidHG. indicates; it was perhaps introduced through a Goth. medium contemporaneously with Kirche and Pfaffe. In E., Whitsunday (Scand. hoítadagr) was retained from a very early period, since it was the chief day for baptism, and the newly baptized were wont to wear white garments during that week; hence the G. term ‘der weiße Sonntag’. (Dominica in Albis). From quinquagesima, the frequent rendering in MidLat. of pentecoste, are derived MidDu. sinxen, OIr. cincgigais, ‘Whitsuntide.’