Irregular Plurals in English (Vocabulary List N° 3)

Vocabulary flashcards detailing irregular plurals, Greek and Latin loanword forms, invariable nouns, and semantic plural distinctions in English.

Essential zero-plural nouns

Nouns whose plural forms remain identical to their singular forms without adding an ending: sheep, deer, fish, aircraft, species, series, and means.

Ox (irregular plural)

Oxen (/ˈɒksən/); irregular plural of ox.

Louse (irregular plural)

Lice (/laɪs/); irregular plural of louse.

Goose (irregular plural)

Geese (/ɡiːs/); irregular plural of goose.

Plurals in -ves rule

A pattern where nouns ending in -f or -fe change to -ves in the plural: leaf → leaves, life → lives, wife → wives, knife → knives, wolf → wolves, half → halves, loaf → loaves, shelf → shelves, thief → thieves, calf → calves, and self → selves.

Exceptions to the -ves rule

Nouns ending in -f or -fe that do not take -ves, taking only -s: roof → roofs, belief → beliefs, chief → chiefs, and safe → safes.

Scarf (plural forms)

A noun that accepts two plural forms: scarves (/skɑːvz/) or scarfs (/skɑːfs/).

Greek/Latin -is to -es plurals

Singular nouns ending in -is that replace the ending with -es in the plural: analysis → analyses, crisis → crises, thesis → theses, hypothesis → hypotheses, diagnosis → diagnoses, basis → bases, and axis → axes.

Phenomenon (plural)

Phenomena (/fəˈnɒmɪnə/); Greek/Latin neuter plural form.

Criterion (plural)

Criteria (/kraɪˈtɪəriə/); Greek neuter plural form.

Datum (plural)

Data (/ˈdeɪtə/ or /ˈdɑːtə/); Latin neuter plural form.

Bacterium (plural)

Bacteria (/bækˈtɪəriə/); Latin plural form.

Medium (plural)

Media (/ˈmiːdiə/); Latin plural form.

Curriculum (plural)

Curricula (/kəˈrɪkjʊlə/); Latin plural form.

Stimulus (plural)

Stimuli (/ˈstɪmjʊlaɪ/); Latin masculine plural form.

Nucleus (plural)

Nuclei (/ˈnjuːklaɪ/); Latin masculine plural form.

Alumnus (plural)

Alumni (/əˈlʌmnaɪ/); masculine or mixed plural form referring to former students/graduates.

Alumna (plural)

Alumnae (/əˈlʌmniː/); feminine plural form referring to former female students/graduates.

Memorandum (plurals)

Memoranda (/ˌmeməˈrændə/) or memorandums (/ˌmeməˈrændəmz/).

Formula (plurals)

Formulae (/ˈfɔːmjʊliː/) or formulas (/ˈfɔːmjʊləz/).

Index (plurals)

Indices (/ˈɪndɪsiːz/) or indexes (/ˈɪndeksɪz/).

Appendix (plurals)

Appendices (/əˈpendɪsiːz/) or appendixes (/əˈpendɪksɪz/).

Nouns that look plural but are singular

Nouns ending in -s that take a singular verb: news, mathematics, politics, economics, linguistics, physics, and measles (e.g., 'The news is encouraging').

Politics (usage note)

Treated as singular when referring to the general subject or activity, but can take a plural verb when referring to the politics of a particular issue.

Nouns that are normally plural

Nouns that take a plural verb: people, police, cattle, clothes, scissors, trousers, jeans, glasses, spectacles, thanks, congratulations, surroundings, earnings, belongings, and outskirts.

A pair of

A counting phrase used before dual nouns such as scissors, trousers, jeans, and glasses.

People (usage)

The standard plural of person, used when referring to individuals in general.

Persons (usage)

An alternate plural of person, reserved specifically for formal or legal usage.

Peoples (usage)

The plural of people when used to designate distinct ethnic, cultural, or national groups (e.g., Indigenous peoples).