An etrog (Hebrew: אֶתְרוֹג, a type of citrus fruit, usually
pronounced "esrog") needs to be larger than a hen's egg, preferably
large enough to fit comfortably into one hand. Larger etrogim
(plural), which can be held with two hands, are kosher but are
considered less desirable. Perfectly round etrogim are not kosher,
but there are different opinions on the ideal shape - some prefer a
straight-edged etrog, others prefer them with a "gartel" - shaped
as though they have a belt (the "gartel" worn by Chassidic and
Charedic Jews) around the middle. Slightly bent etrogim can be
kosher but are not considered as desirable.