The following are the three Rules of formation of Feminine Gender from Masculine Gender –

#1. By adding ‘ess, ine, trix, a’ to the word in the Masculine Gender. The addition of ‘ess’ is the most popular. As –

(a) By adding ‘ess’ in the Masculine words –
Masculine
Feminine
Masculine
Feminine
Author
Baron
Count
Giant
Heir
Host
Jew
Lion
Manager
Authoress
Boroness
Countess
Giantess
Heiress
Hostess
Jewess
Lioness
Manageress
Mayor
Patron
Peer
Poet
Priest
Prophet
Shepherd
Steward
Viscount
Mayoress
Patroness
Peeress
Poetess
Priestess
Prophetess
Shepherdess
Stewardess
Viscountess

(b) By removing the last Vowel in the Masculine word before adding ‘ess’ in the following words –
Masculine
Feminine
Masculine
Feminine
Actor
Benefactor
Conductor
Enchanter
Founder
Hunter
Instructor
Abbot
Duke
Emperor
Marquis
Actress
Benefactress
Conductress
Enchantress
Foundress
Huntress
Instructress
Abbess
Duchess
Empress
Marqioness
Preseptor
Prince
Songster
Temptor
Seamaster
Tiger
Traitor
Waitor
Master
Murderer
Sorcerer
Preseptress
Princess
Songstress
Temptress
Seamistress
Tigress
Traitress
Waitress
Mistress
Murdress
Sorceress

(c) By adding  ‘ine’, ‘trix’, ‘a’ –
Masculine
Feminine
Masculine
Feminine
Hero
Administrator
Executor
Testator
Heroine
Administratrix
Executrix
Testatrix
Czar
Sultan
Signor
Fox
Czarina
Sultana
Signora
Vixen

#2. By adding an entirely new word before or after the Masculine word. As –

Masculine
Feminine
Masculine
Feminine
Bull-calf
Cock-sparrow
He-goat
He-bear
Jackçass
Man-metchant
Cow-calf
Hen-sparrow
She-goat
She-bear
Jenny-ass
Maid-merchant
Grandfather
Great-uncle
Landlord
Milk-man
Peacock
Washerman
Grandmother
Great-aunt
Landlady
Milkmaid
Peahen
Washerwoman

#3. The feminines of the following Masculines are quite different from their originals. As –
Masculine
Feminine
Masculine
Feminine
Bachelor
Boy
Brother
Buck
Bull/ox
Bullock
Cock
Colt
Dog
Drake
Drone
Earl
Father
Gander
Gentleman
Maid/spinster
Girl
Sister
Doe
Cow
Heifer
Hen
Filly
Bitch
Duck
Bee
Countess
Mother
Goose
Lady
Hart
Horse
Husband
King
Lord
Man
Monk/Friar
Nephew
Papa
Sir
Ram
Stay
Son
Uncle
Wizard
Roe
Mare
Wife
Queen
Lady
Woman
Nun
Niece
Mamma
Madam
Ewe
Hind
Daughter
Aunt
Witch