Plural of Basis

The Quick Answer

The plural of basis is bases.

The Plural of Basis

The plural of basis is bases.

What are the bases of promotion?
Many countries are united in their belief in freedom, democracy, and human rights. However, these same beliefs are the bases of their division.

The noun basis has a Greek root, which is the derivation of the plural bases. There is no alternative English plural form. The noun basis adheres to the standard rules for forming the plurals of nouns in English (shown in the table below).

Type	Example of Type	Forming the Plural	Plural
Most Nouns	lamp scythe	add s	lamps scythes
Noun Ending s, sh, ch, x or z	box dress	add es	boxes dresses
Nouns ending [consonant] o	zero tomato	add either s or es (There are no rules for this - you have to know.)	zeros tomatoes
Nouns ending [vowel] o	patio ratio	add s	patios ratios
Nouns ending [consonant] y	story penny	change the y to an i and add es	stories pennies
Nouns ending [vowel] y	donkey chimney	add s	donkeys chimneys
Nouns ending f or fe	dwarf hoof	ves and/or s (There are no rules - you have to know.)	dwarfs hooves or hoofs
Nouns ending is	basis thesis	change the is to es	bases theses
Exceptions	man louse	some nouns undergo a vowel or letters change	men lice
More exceptions	salmon sheep	some nouns do not change at all	salmon sheep
Foreign rulings	fungus medium	some nouns adopt foreign rulings	fungi media

Why Is There Confusion over the Plural of basis?

bases is the only way to make the noun basis plural.

Confusion arises because some mistakenly believe that all nouns ending in s should form a plural that adds es to the end of the word. When a noun ends with is, you need to replace the is with an es to form the plural. This is because its plural form derives from Greek.

Of note, the plural bases is also the plural form of the noun base.

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