SVA Rule #15. 

Some of the nouns in English are irregular, they do not take -s/es as plurals. You need to learn these irregular nouns.

1. Irregular plural forms
man – men;
woman – women;
child – children;
ox – oxen;
mouse – mice;
louse – lice;

foot – feet;
tooth – teeth;
goose – geese.

4. Only in the plural
jeans; trousers, pants, slacks;
shorts, tights, breeches;
pajamas, briefs, panties;
scissors, pliers, tongs, pincers, forceps;
glasses, spectacles.

2. The same singular form
one sheep – two sheep;
a deer – two deer;
a bison – five bison;
a moose – three moose;
a swine – several swine;
a fish – two fish;
a dozen – two dozen;
an aircraft – two aircraft;

5. Only in the singular
No news is good news. (proverb)
Billiards is an interesting game.
Measles is a serious disease.
Mathematics is his favorite subject.

3. The same plural form
a means – means;
a series – two series;
a species – different species;
a corps – corps;
a headquarters – headquarters;
a crossroads – crossroads;
an alms – alms;
a gallows – gallows;
a barracks – barracks.

6. Nouns ending in “ics”
Acoustics is a branch of physics.
The acoustics of this concert hall are excellent.
She studied economics in college.
What are the economics of this project?
He is studying politics.
What are his politics?



7. Latin and Greek plural forms

Group 1
analysis – analyses
axis – axes
basis – bases
crisis – crises
diagnosis – diagnoses
ellipsis – ellipses
emphasis – emphases
genesis – geneses
hypothesis – hypotheses
oasis – oases
parenthesis – parentheses
synopsis – synopses
synthesis – syntheses
thesis – theses

Group 4, Cont.
medium – mediums
memorandum – memorandums (E), memoranda
millennium – millenniums (E), millennia
planetarium – planetariums (E), planetaria
podium – podiums (E), podia
spectrum – spectra, spectrums (E)
stadium – stadiums (E), stadia
sternum – sterna, sternums (E)
stratum – strata, stratums (E)
symposium – symposiums (E), symposia
terrarium – terrariums (E), terraria
vacuum – vacuums (E), vacua
vivarium – vivariums (E), vivaria

Group 2
abacus – abacuses (E), abaci
alumnus – alumni
apparatus – apparatus, apparatuses (E)
cactus – cactuses (E), cacti
calculus – calculi, calculuses (E)
corpus – corpora
eucalyptus – eucalyptuses (E), eucalypti
focus – focuses (E), foci
fungus – fungi, funguses (E)
genus – genera, genuses (E)
hippopotamus – hippopotamuses (E), hippopotami
nucleus – nuclei, nucleuses (E)
octopus – octopuses (E), octopi
papyrus – papyri, papyruses (E)
platypus – platypuses (E), platypi
radius – radii, radiuses (E)
rhombus – rhombuses (E), rhombi
stimulus – stimuli
stylus – styluses (E), styli
syllabus – syllabuses (E), syllabi
terminus – termini, terminuses (E)

Group 5
alumna – alumnae
antenna – (radio) antennas
antenna – (insects) antennae
vertebra – vertebrae, vertebras (E)

Group 3
automaton – automatons (E), automata
criterion – criteria
phenomenon – phenomena
polyhedron – polyhedrons (E), polyhedra
octahedron – octahedrons (E), octahedra
tetrahedron – tetrahedrons (E), tetrahedra

Group 6
charisma – charismata
dogma – dogmas (E), dogmata
enigma – enigmas (E), enigmata
formula – formulas (E), formulae
stigma – stigmata, stigmas (E)

Group 4
addendum – addenda
aquarium – aquariums (E), aquaria
arboretum – arboretums (E), arboreta
atrium – atria, atriums (E)
bacterium – bacteria
compendium – compendiums (E), compendia
curriculum – curriculums (E), curricula
datum – data
emporium – emporiums (E), emporia
equilibrium – equilibriums (E), equilibria
erratum – errata
forum – forums (E), fora
maximum – maximums (E), maxima
medium – media

Group 7
apex – apexes (E), apices
appendix – appendixes (E), appendices
index – indexes (E), indices
matrix – matrices, matrixes (E)
vertex – vertexes (E), vertices

 Example #30. 

The pneumococcal bacterium is the second most common cause of bacterial meningitis. More than 90 different strains of the pneumococcal bacterium have been identified, though only between eight and 10 of them cause the most serious infections.

  2. is … has
  3. are … has
  4. are … have


Click to see the correct answer The correct answer is choice A.