omer

noun4

1. •
   (historical) A former small Hebrew unit of dry volume equal to about 2.3 L or 2.1 quarts.

   • ...that Omer which was every mans daily portion of Manna, is computed to have bin more then might have well suffic'd the heartiest feeder thrice as many meals. — 1644
2. •
   (Judaism) The counting of the omer, that is, the period of 49 days between Passover and Shavuot.
3. •
   (Judaism) The sheaf of barley offered on the second day of Passover.
4. •
   A vessel of one omer.

noun1

1. •
   (Judaism) The 49-day period from the second day of Passover to Shavuot, begun and ended with an offering of a sheaf of barley and noted nightly during evening prayer.

   • The counting of the Omer—the Sefiras HaOmer—is a mitzvah.