Kezayit, k'zayit, or kezayis () is a Talmudic unit of volume approximately equal to the size of an average

olive The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...

. The word itself literally means "like an olive." The rabbis differ on the precise definition of the unit: * Rabbeinu Yitzchak (the Ri) defines it as one-half of a beytza (a beytza is the volume of an egg). * Maimonides specified that a 'grogeret' (dried fig) was one-third of a beytza, making this the maximum size for a kezayit, which is smaller. Rabbeinu Tam made the argument explicitly, though, using a slightly different calculation came out with a maximum definition of three-tenths. * According to some interpretations, including the Chazon Ish, the ''zayit'' is not related to other units by a fixed ratio, but rather should only be conceived of independently as the size of an average olive. Its uses in halacha include: * The minimum amount food that, when eaten, is halachically considered "eating." This has implications throughout the spectrum of halacha, including: ** For prohibitions of consumption, as in the eating of '' milk and meat'' ** For the saying of a Bracha Ahrona (the traditional grace after meals) * People exposed to at least a ''kezayit'' of the flesh of a dead body become ritually impure.

See also