There are three ways of forming the feminine gender:

1.    By using an entirely different word
Examples are given below:

• Boy (masculine), girl (feminine)
• Man, woman
• Brother, sister
• Bull, cow
• Horse, mare
• Husband, wife
• Cock, hen
• Earl, countess
• Gander, goose
• Gentleman, lady

2.    By adding a syllable (-ess, -ine, -trix, -a etc.)

• Author (masculine) authoress (feminine)
• Baron, baroness
• Count, countess
• Heir, heiress
• Host, hostess
• Lion, lioness
• Patron, patroness
• Hero, heroine
• Czar, czarina
• Fox, vixen

3.    By placing a word before or after

• Grandfather (masculine), grandmother (feminine)
• Landlord, landlady
• Peacock, peahen
• Salesman, saleswoman

Related posts:

1. Noun: Gender