What is "feast of weeks"

Pentecost \Pen"te*cost\, n. [L. pentecoste, Gr. ? (sc. ?) the fiftieth day, Pentecost, fr. ? fiftieth, fr. ? fifty, fr. ? five. See Five, and cf. Pingster.]

1. A solemn festival of the Jews; -- so called because celebrated on the fiftieth day (seven weeks) after the second day of the Passover (which fell on the sixteenth of the Jewish month Nisan); -- hence called, also, the Feast of Weeks. At this festival an offering of the first fruits of the harvest was made. By the Jews it was generally regarded as commemorative of the gift of the law on the fiftieth day after the departure from Egypt.

2. A festival of the Roman Catholic and other churches in commemoration of the descent of the Holy Spirit on the apostles; which occurred on the day of Pentecost; -- called also Whitsunday.
   --Shak.

Week \Week\, n. [OE. weke, wike, woke, wuke AS. weocu, wicu, wucu; akin to OS. wika, OFries. wike, D. week, G. woche, OHG. wohha, wehha, Icel. vika, Sw. vecka, Dan. uge, Goth. wik?, probably originally meaning, a succession or change, and akin to G. wechsel change, L. vicis turn, alternation, and E. weak. Cf. Weak.] A period of seven days, usually that reckoned from one Sabbath or Sunday to the next. I fast twice in the week. --Luke xviii. 12. Note: Although it [the week] did not enter into the calendar of the Greeks, and was not introduced at Rome till after the reign of Theodesius, it has been employed from time immemorial in almost all Eastern countries. --Encyc. Brit. Feast of Weeks. See Pentecost,

1. Prophetic week, a week of years, or seven years.
   --Dan. ix. 24.

   Week day. See under Day.