Beyond the common knowledge

[ابراهيم موسى]

Thank you so much Mr Sw0rdD
May Allah bless you
I always love and appreciate your lovely ideas and effective participations
Concerning unusual plurals I have found a very useful site ,here`s the link
http://www.hintsandthings.co.uk/library/plurals.htm
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Some words are the same in both singular and plural forms, these I have shown in green.
SINGULAR PLURAL

attorney general

attorneys general

Heidi Kroening

bacterium

bacteria

bison

bison

Bob Bartels

cactus

cacti

Heather

child

children

Katie Barlow & daughter

corps

corps

Margarita Minster

cow

kine

(old fashioned term)

Gary Engel

cod

cod

Margarita Minster

criterion

criteria

cul-de-sac

culs-de-sac

Louis Hegedus

datum

data

deer

deer

Bob Bartels

diagnosis

diagnoses

die

dice

elf

elves

Bob Bartels

fish

fish

(or fishes)

Margarita Minster

Focus

Foci

Charles Rowan

foot

feet

Gigi Velazquez

formula

formulae

Katie Barlow & daughter

fowl

fowl
(or fowls)

Margarita Minster

genius

geniuses

Richard Hill

or genii

goose

geese

Katie Barlow & daughter

graffito

graffiti

halibut

halibut

Margarita Minster

hippopotamus

hippopotami

Heather

More commonly used hippopotamuses see ***

louse

lice

man

men

Katie Barlow & daughter

man-of-war

men of war

Heidi Kroening

means

means

Margarita Minster

Medium

Media

Charles Rowan

mongoose

mongooses

moose

moose

Margarita Minster

mouse

mice

medium

media

offspring

offspring

Margarita Minster

octopus

octopuses ***

Richard Hill

perch

perch

(or perches)

Margarita Minster

person

people

Katie Barlow & daughter

phenomenon

phenomena

pike

pike

(when referring to fish)

Margarita Minster

polyhedron

polyhedra

Heidi Kroening

polyhedrons*

* alternative form

quantum

quanta

radius

radii

Jeremy Symons

salmon

salmon

(or salmons)

Margarita Minster

scissors

scissors

Margarita Minster

series

series

Margarita Minster

sheep

sheep

Margarita Minster

species

species

Margarita Minster

stratum

strata

tooth

teeth

Katie Barlow & daughter

trout

trout

(or trouts)

Margarita Minster

tuna

tuna

(or tunas)

Margarita Minster

woman

women*

Katie Barlow & daughter