A noun that refers to a male animal is said to be of the masculine gender. Note that the noun gender comes from the Latin word genus which means kind or sort.

Examples are: boy, cock, bull, lion, hero, man, brother, son etc.

A noun that refers to a female animal is said to be of the feminine gender. Examples are: girl, hen, cow, lioness, heroine, woman, sister, daughter etc.

A noun that can refer to either a male or a female is said to be of the common gender. Examples are: parent, student, teacher, doctor, child, friend, cousin, baby, neighbor etc.

A noun that refers to a thing that is neither male nor female is said to be of the neuter gender.
Examples are: book, pen, paper, stone, tree, star etc.

Inanimate objects (objects without life) are often personified and spoken of as if they were living beings. These nouns are then regarded as males or females.

Note that the masculine gender is often applied to objects remarkable for their strength. Examples are: The Sun, Time, Death, Summer, Winter etc.

The sun sheds his beam on rich and poor alike. (Here the inanimate object sun is spoken of as a male.)

The feminine gender is sometimes applied to objects remarkable for their beauty and gracefulness. Examples are: the moon, spring, autumn, nature, peace, mercy, hope etc.

The moon hid her face behind a cloud.

Formation of feminine gender

Nouns of the feminine gender are formed in a number of ways:

1.    By using an entirely different word

Examples are given below:

Man (masculine), woman (feminine)
Boy, girl
Father, mother
Horse, mare
Dog, bitch
Husband, wife
Cock, hen
King, queen
Monk, nun
Gentleman, lady

2.    By adding a syllable (-ess, -ine, -trix,-a etc.) to the masculine noun

Author (masculine), authoress (feminine)
Baron, baroness
Count, countess
Giant, giantess
Heir, heiress
Host, hostess
Lion, lioness
Poet, poetess
Priest, priestess
Prince, princess