Irregular Plurals: Nouns Ending in -f

Irregular Plurals: Nouns Ending in -f changing to -ves
Some nouns that end in -f or -fe in the singular form change their ending to -ves in the plural form.
This is a common type of irregular plural formation in English.
Examples include:
Singular: calf; Plural: calves
Singular: elf; Plural: elves
Singular: half; Plural: halves
Singular: knife; Plural: knives
Singular: leaf; Plural: leaves
Singular: life; Plural: lives
Singular: loaf; Plural: loaves
Singular: self; Plural: selves
Singular: sheaf; Plural: sheaves
Singular: shelf; Plural: shelves
Singular: thief; Plural: thieves
Singular: wife; Plural: wives
Singular: wolf; Plural: wolves
Exceptions and Variations:
Not all nouns ending in -f follow this rule.
Some nouns ending in -f simply add an -s to form the plural.
Examples of nouns that add -s: chief/chiefs, roof/roofs, cliff/cliffs, puff/puffs, belief/beliefs, chef/chefs, proof/proofs.
Some nouns can take either the -s or -ves plural form, such as scarf (scarfs or scarves) and wharf (wharfs or wharves), although usage may vary by region or personal preference.
The word "staff" has two plurals with different meanings: staffs (referring to objects) and staff (referring to a group of people).
"Hoof" can be hooves or hoofs.
Irregular Plurals: Nouns Ending in -en
A smaller group of nouns form their plural by adding -en or -ren.
This is a less common type of irregular pluralization in modern English.
Examples include:
Singular: child; Plural: children
Singular: ox; Plural: oxen
Singular: brother; Plural: brethren (archaic/formal, "brothers" is more common)
Notes:
"Children" is the most commonly encountered example of this type.
"Oxen" is mainly used in specific agricultural contexts.
"Brethren," while still found, is largely replaced by "brothers" in contemporary usage except in specific religious or fraternal contexts.
Mutant or Vowel Change Plurals
These nouns change the vowel sound in the word to indicate the plural form.
This is a distinct and relatively small category of irregular plurals.
Examples include:
Singular: foot; Plural: feet
Singular: goose; Plural: geese
Singular: tooth; Plural: teeth
Singular: mouse; Plural: mice
Singular: louse; Plural: lice
Notes:
These plurals do not follow a predictable pattern, making them irregular.
"Man","woman", "person" and "salesman" etc also follow this rule of vowel change.
Replacing "a" with "e" creates the plural; men, women, people, salesmen.
Foreign Plurals
Some nouns retain their original plural forms from the languages they were borrowed from (often Latin, Greek, or French).
These can be challenging as they don't follow standard English pluralization rules.
Examples from Latin:
Singular: alumnus; Plural: alumni (male graduate)
Singular: alumna; Plural: alumnae (female graduate)
Singular: curriculum; Plural: curricula
Singular: focus; Plural: foci
Singular: formula; Plural: formulae or formulas (formulas is also accepted)
Singular: index; Plural: indices or indexes (indexes is also accepted)
Singular: matrix; Plural: matrices
Singular: memorandum; Plural: memoranda or memorandums (memorandums is also accepted)
Singular: stadium; Plural: stadia or stadiums (stadiums is also accepted)
Singular: cactus; Plural: cacti or cactuses (cactuses is also accepted)
Examples from Greek:
Singular: analysis; Plural: analyses
Singular: axis; Plural: axes
Singular: crisis; Plural: crises
Singular: hypothesis; Plural: hypotheses
Singular: phenomenon; Plural: phenomena
Singular: criterion; Plural: criteria
Examples from French:
Singular: bureau; Plural: bureaux
Singular: madame; Plural: mesdames
Singular: monsieur; Plural: messieurs
Notes:
Many of these nouns are increasingly accepting standard English plural forms (adding -s or -es) in informal contexts.
The "correct" plural can depend on the level of formality and the audience.
It is important to be aware of both the foreign plural and the accepted English plural.
Usage can vary, with some foreign plurals becoming increasingly rare.
Dictionaries are a good resource for determining the preferred plural form.