Pentecosten

According to the Old English Dictionary:

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Pentecosten

m. (?) Pentecost, the fiftieth day after the resurrection, Whitsuntide :-- On Pentecostenes dæg com se Hálga Gást ofer ða apostolas, Btwk. 214, 29. On ðære Pentecostenes wucan, Rubc. Lk. Skt. 5, 17 : 8, 40. On óðerne Pentecostenes mæssedæg, Rubc. Jn. Skt. 3, 16. On Pentecostenes mæsseǽfen, 14, 15. pentecosten