deer-deer

fish-fish

moose-moose

offspring-offspring

sheep-sheep

species – species

foot-feet

goose-geese

tooth-teeth

(brother-brethren)

child-children

man-men

ox-oxen

woman-women

louse-lice

mouse-mice

banjo – banjo(e)s

buffalo – buffalo(e)s

cargo – cargo(e)s

dingo – dingoes

domino – domino(e)s

echo – echoes

embargo – embargoes

flamingo – flamingo(e)s

gecko – geckoes

ghetto – ghetto(es)

halo – halo(e)s

hero – heroes

hobo – hoboes

mango – mango(e)s

memento – memento(e)s

mosquito – mosquito(e)s

motto – motto(e)s

potato – potatoes

tomato – tomatoes

tornado – tornadoes

torpedo – torpedoes

tuxedo – tuxedo(e)s

veto – vetoes

volcano – volcano(e)s

alumnus – alumni

bacillus – bacilli

bronchus – bronchi

cactus – cacti

calculus – calculi

embolus – emboli

focus – foci

fungus – fungi

meniscus – menisci

nucleus – nuclei

radius – radii

stimulus – stimuli

terminus – termini
 

anastomosis – anastomoses

axis – axes

analysis – analyses

basis – bases

crisis – crises

diagnosis – diagnoses

ellipsis – ellipses

emphais – emphases

hypothesis – hypotheses

neurosis – neuroses

oasis – oases

paralysis – paralyses

parenthesis –parentheses

prognosis – prognoses

prosthesis – prostheses

synthesis – syntheses

synopsis -synopses

thesis – theses

bandeau – bandeaux

beau – beax

bureau – bureaux

chateau – chateaux

flambeau – flambeaux

gateau – gateaux

plateau – plateaux

portmanteau -portmanteaux

tableau – tableaux

tonneau – tonneaux

trousseaux – trousseaux

alga – algae

amoeba – amoebae

antenna – antennae

formula – formulae

larva – larvae

nebula – nebulae

vertebra – vertebrae

vita -vitae

apex – apices

cervix – cervices

appendix – appendices

index – indices

matrix – matrices

vertex – vertices

vortex – vortices

addendum – addenda

bacterium – bacteria

curriculum – curricula

datum – data

erratum – errata

diverticulum – diverticula

epithelium – epithelia

medium – media

memorandum – memoranda

ovum – ova

stratum – strata

symposium – symposia

automaton – automata

criterion – criteria

ganglion – ganglia

phenomenon – phenomena

spermatozoon – spermatozoa

corpus – corpora

genus – genera

foramen – foramina

lumen – lumina

libretto – libretti

tempo – tempi

virtuoso – virtuosi

cherub – cherubim

seraph – seraphim