Many English words simply require adding an ‘s’ when forming a plural. ‘Table’, for example, becomes ‘tables’. There are, however, a host of words that don’t stick to this rule. These are known as irregular plurals.
Luckily, there are some guidelines which can help you spell irregular plurals correctly. These aren’t strict rules, as there are always exceptions, but they can help while writing. As ever, though, if in doubt, check a dictionary.
Often, these guidelines relate to the ending of a word.
Words ending ‘-us’ (e.g. ‘alumnus’) often take the plural ending ‘-i’ (e.g. ‘alumni’). Other such words include:
Singular
Plural
Nucleus
Nuclei
Radius
Radii (pronounced ‘ray-dee-eye’)
Cactus
Cacti
Stimulus
Stimuli
Note that the word ‘virus’ does not follow this pattern and is spelled ‘viruses’ in the plural. In addition, in some cases the ‘i’ ending is considered old-fashioned. For example, although ‘hippopotami‘ is accepted as a plural of ‘hippopotamus’, ‘hippopotamuses‘ is more common in modern English.
Words ending ‘-on’ (e.g. ‘phenomenon’) often take the plural ending ‘-a’ (e.g. ‘phenomena’). Other words which follow this pattern include:
Criterion
Criteria
Referendum
Referenda
Curriculum
Curricula
Bacterium
Bacteria
As above, though, sometimes using the ‘-a’ ending can seem old-fashioned. ‘Stadia‘, for instance, is accepted as a plural of ‘stadium’, but ‘stadiums‘ is much more common these days.
Subscribe to our newsletter and get writing tips from our editors straight to your inbox.
Words ending ‘-f’ or ‘-fe’ (e.g. ‘leaf’ and ‘knife’) typically replace the ‘-f’ or ‘-fe’ with ‘-ves’ in the plural (e.g. ‘leaves’ and ‘knives’). Other such words include:
Wife
Wives
Hoof
Hooves
Wolf
Wolves
Thief
Thieves
There are, however, multiple exceptions to this rule, including ‘beliefs’, ‘chiefs’, ‘reefs’ and ‘cuffs’.
Words ending in ‘-is’ (e.g. ‘analysis’) take the plural ending ‘-es’ (e.g. ‘analyses’). See also:
Axis
Axes
Basis
Bases
Hypothesis
Hypotheses
Crisis
Crises
There are also words which are spelled the same in the singular and the plural. Examples include ‘moose’, ‘deer’, ‘sheep’, ‘equipment’ and ‘furniture’. Thus, one can speak both of a single ‘sheep’ and a ‘flock of sheep’.
If you would like further guidance about spelling or academic writing, or to have a 500-word sample of your writing proofread for free, get in touch with the professionals at Proofed today!
Δ
2-minute read
If you’re writing about health issues, you might need to reference the Centers for Disease...
5-minute read
Introduction If you’re involved with ecommerce, you’re likely familiar with the often painstaking process of...
3-minute read
Are you interested in learning more about the role of a content editor and the...
4-minute read
Proofreading is important to ensure your writing is clear and concise for your readers. Whether...
Creating presentations can be time-consuming and frustrating. Trying to construct a visually appealing and informative...
No matter your industry, conducting market research helps you keep up to date with shifting...