An oocyte, ovocyte, or rarely ocyte, is a female gametocyte

Gametocyte

A gametocyte is a eukaryotic germ cell that divides by mitosis into other gametocytes or by meiosis into gametids during gametogenesis. Male gametocytes are called spermatocytes, and female gametocytes are called oocytes....

 or germ cell

Germ cell

A germ cell is any biological cell that gives rise to the gametes of an organism that reproduces sexually. In many animals, the germ cells originate near the gut of an embryo and migrate to the developing gonads. There, they undergo cell division of two types, mitosis and meiosis, followed by...

 involved in reproduction

Biological reproduction

Reproduction is the biological process by which new "offspring" individual organisms are produced from their "parents". Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction...

. In other words, it is an immature ovum

Immature ovum

An immature ovum is a cell that goes through the process of oogenesis to become an ovum. It can be an oogonium, an oocyte or an ootid. An oocyte, in turn, can be either primary or secondary, depending on how far it has come in its process of meiosis....

, or egg

Ovum

An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...

 cell. An oocyte is produced in the ovary during female gametogenesis

Gametogenesis

Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes,...

. The female germ cells produce a primordial germ cell (PGC) which undergoes a mitotic division

Mitosis

Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...

 to form an oogonium. During oogenesis the oogonium becomes a primary oocyte .

The formation of an oocyte is called oocytogenesis, which is a part of oogenesis.