From Wikipedia, the free encyclopedia
A pullet is a young chicken, more specifically a hen (female) at least 20-weeks-old which has begun to lay eggs but has not yet moulted.
From another site..
a young chicken is called a chick. a male chicken is a cock or a cockerel, depending on its age. similarly, a female chicken is called a pullet or a hen. the age at which a pullet becomes a hen and a cockerel becomes a cock depends on what type of chicken is being raised. purebred poultry producers have very age-specific definitions. a chicken is a cockerel or pullet if it is less than one year of age.
after one year of age, the chicken is referred to as a hen or cock. in the commercial industry a female chicken is called a hen after it begins egg production (around five months of age). a sexually mature male chicken (again, around five months of age) is referred to as a rooster. a capon is a castrated male chicken.