Pen·te·cost (pĕntĭ-kôst′, -kŏst′)
1. Christianity The seventh Sunday after Easter, commemorating the descent of the Holy Spirit upon the disciples. Also called Whitsunday.
2. Judaism See Shavuot.
[Middle English pentecoste, from Old English pentecosten, from Late Latin Pentēcostē, from Greek pentēkostē (used as a translation of Hebrew šābû‘ôt, Shavuot), from pentēkostē (hēmerā), fiftieth (day), feminine of pentēkostos, fiftieth, from pentēkonta, fifty; see penkwe in the Appendix of Indo-European roots.]
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Indo-European & Semitic Roots Appendices
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