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Glass’s or Glass’: Which is Correct?

While the apostrophe might seem to be a simple concept in English grammar, it can turn out to be tricky at times, even for native English speakers. For example, most people think they know everything regarding plural and possessive forms; however, they sometimes make mistakes, and the apostrophe can be the culprit.

The word “glass’s” is the singular possessive form of the noun “glass.” The plural form of “glass” is “glasses,” and the plural possessive form is, therefore, “glasses’.” Most academic style guides consider “glass’” incorrect because “glass” is singular, and the same guides generally recommend only adding an apostrophe on its own after plural nouns ending with “s.”

This article will consider the singular and plural possessive forms, particularly relating to issues using apostrophes that might confuse those new to the English language. We’ll also examine the various definitions of the word “glass” and the challenges these can pose.

Is It Glass’s Or Glass’?

Singular PossessiveGlass’s
Plural PossessiveGlasses’

We often use the word “glass” either when referring to the substance in a drinking vessel or a drinking vessel itself. The plural form is “glasses,” which is appropriate in certain contexts. 

As we’ll discuss later, we generally add -‘s to nouns to create singular possessive forms. Thus, in the case of “glass,” the correct plural possessive form is “glass’s.”

We only add the apostrophe on its own to plurals nouns like “glasses” to show possession, so adding it to the singular word “glass” as in “glass’” is incorrect. However, there is disagreement as to proper nouns like personal names and the names of states, which we’ll also explain.

Knowing whether to use “glass’s” or “glass’” requires understanding how the possessive form works and being clear on whether a word is singular or plural in form. 

To show that a noun has ownership of something, you will also have to use and understand apostrophes. At times, they come before an “s,” and, at other times, they come after. Also, as you can see, there are cases when using an apostrophe after “s” is not valid. 

Similar confusion arises with words like class’s and class’. Click here to read more about this.

Why Is There  Confusion Over the Plural Form of Glass?

People sometimes make the mistake of using “glass’” as the plural form of “glass.” However, that is incorrect, and the plural form, where applicable, is always “glasses.” As you will learn, it depends on the meaning as to whether there is a plural form or not. 

When you talk about “glass” as a substance, it is a mass noun. A mass noun is a type of noun that does not have any kind of plural form. Mass nouns refer to all those items that we cannot count, for example, milk, music, etc. 

But when you refer to a “glass” as a drinking container, it can change into the plural form “glasses.” However, we often use “glasses” in the plural as another word for “spectacles,” and the singular “glass” does not apply to spectacles. 

Image by Oli Woodman via Unsplash

Distinguishing the Usages of Glass as a Noun

“Glass” is one of those words that has several related definitions. You must be clear about how you are using the word because that will impact its possessive form as well as whether it has a plural form. 

As a noun, it can be any of the following (source):

  • a hard, usually transparent material formed from a melt and cooled to a rigid form. 
  • objects made of glass and considered as a group
  • a drinking container
  • quantity of liquid contained in a glass container

The sentences below illustrate how you can use the word in context for each of these definitions:

  • The architect uses plenty of glass in his designs. (the hard, transparent material)
  • She displayed her collection of blue glass. (glass objects considered as a group)
  • Be careful not to break that glass. (a drinking container)
  • Would you like a glass of water? (quantity of liquid)

“Glass” can also function as a verb, but this is far less common and doesn’t apply to the possessive form. We can use the verb “glass” in the sense of glazing, encasing something in glass, or making something glassy.

Standard Rules for Forming Plurals

When dealing with possessive nouns, it’s important to know whether they are singular or plural. Forming plurals in the English language is simple for most words, but you’ll have to learn some exceptions. Here is a table that will help you with the formation of plurals.

TypeExamplePlural FormationPlural
Standard NounsCatAppleAdd “s”CatsApples
Nouns ending with “s,” “ch,” “sh,” “x,” or “z”GlassBranchAdd “es”GlassesBranches
Nouns ending with “o” preceded by a consonantZeroMangoYou can add either “es” or “s” (There is no specific rule for this)Zeros or ZeroesMangos or Mangoes
Nouns ending with “o” preceded by a vowelRatioPatioAdd “s”RatiosPatios
Nouns ending with “y” preceded by a consonantPennyStoryChange “y” to “i” and add “es”PenniesStories
Nouns ending with “y” preceded by a vowelDonkeyAdd “s”Donkeys
Mass nounsRiceGlassMass nouns do not have any plural formGlassRice
Nouns ending with “fe” or “f”KnifeDwarfAdd “s” and/or “ves”KnivesDwarfs
ExceptionsLouseGooseCertain nouns undergo a letter or vowel changeLiceGeese
Additional exceptionsSheepSalmonCertain nouns do not undergo any changeSheepSalmon

Singular Possessive Nouns

Singular possessive nouns are quite easy. When a place, person, or thing owns something, you just need to add “‘s.”


  • John’s dog is very aggressive.
  • Sam’s coat is too short.

You know that a noun is a word that names a place, person, idea, or thing. Some examples of nouns would be “horse” or “teacher.” You use the possessive form of a noun to show ownership by a specific noun. 

You can use a possessive form to indicate that someone owns something, such as a teacher’s bag or a friend’s car. So, to demonstrate that “my friend” (which is singular) has a car, you can change the noun “friend” into the singular possessive form simply by adding an “s” and apostrophe (source). 


  • My friend’s car is brand new.
  • I do not like that restaurant’s food.
  • The horse’s tail is very long.

Most nouns take a simple -‘s, but some specific rules govern the spelling of singular possessive nouns. 

Singular Noun Ending With “s”

The rule also applies when the singular noun you want to change to the singular possessive form already ends with an “s.”


  • The class’s boys are so talkative.
  • I would like to change the glass’s water.

However, there is some debate regarding whether you should include -’s after all kinds of singular words that end with “s.” 

  • Texas’s hotels or Texas’ hotels?
  • Travis’s books or Travis’ books?

Strunk and White’s The Elements of Style states that no matter what the final consonant is, you need to add -’s. The Chicago Manual of Style favors this rule from Strunk and White to a great extent (CMOS 7.17), and they do not recommend the alternative because it tends to overlook pronunciation (CMOS 7.22) (source).

Other academic style guides like the American Psychological Association (APA) and Modern Language Association (MLA) favor an apostrophe-s for proper names ENDING WITH “s” (source).

However, one non-academic style that favors using only an apostrophe at the end of words ending in “s” would be the Associated Press Stylebook (source). AP Style suggests using only an apostrophe for proper nouns that end with “s” and also for common nouns that end with “s” if the next word starts with an “s.” 

  • Texas’s streets (CMOS)
  • Texas’ streets (AP)
  • Travis’s schoolwork (CMOS)
  • Travis’ schoolwork (AP)
  • That business’s system (CMOS)
  • That business’ system (AP)
  • The glass’s straw (CMOS
  • The glass’ straw (AP)

One exception for the Chicago Manual of Style is “For…sake” expressions, like “For goodness’ sake” (CMOS 7.21). Yet AP Style would accept the apostrophe even for words that sound like the end in “s,” as in “for conscience’ sake,” while CMOS would have “For conscience’s sake.”

Singular Noun Ending With “z” or “x”

The basic rules remain the same for all kinds of singular nouns that end in either “z” or “x,” which is one of the most common areas where people make mistakes.


  • Dr. Mendez’s class was quite interesting.
  • Miss Delacroix’s car broke down yesterday.

Joint Possession

You might sometimes have to use what grammarians refer to as “joint possession.” This occurs when two or more individuals own something together. For example, it might be the case that a husband and wife own a house jointly or two siblings share one bedroom. In that case, you add an apostrophe-s only at the end of the last noun.


  • Jack and Amanda’s new house looks great. 
  • Jane and Keisha’s bedroom is so well organized. 

If you want to communicate that several individuals own separate things in a sentence, you will express this differently. For instance, if Marc and Ron have finished their separate tests, we will use an “s” and an apostrophe at the end of each noun, signaling to the reader that there is separate ownership.


  • Marc’s and Ron’s tests went well.
  • Tisha’s and Marco’s rooms look so cute.

Plural Possessive Nouns

Plural possessive nouns can turn out to be a bit challenging. Plural possessive nouns show ownership by more than one of something and generally end with an apostrophe where the plural ends in an “s.”


  • The dogs’ toys are in the garden.
  • The books’ pages are completely ruined.

Again, there are rules that govern the spelling of plural possessive nouns and give guidance for exceptions.

Plural Noun Ending With “s”

The majority of plural nouns end with “s.” In that case, all you need to do is add an apostrophe to show possession by the group.


  • The executives’ decision is final.
  • The dogs’ treats are here.
  • The stores’ management is awful.

Now, when it comes to “glasses,” it acts as a plural noun in form but singular in meaning (CMOS 7.20). It functions as the short form for a pair of glasses or even pairs of glasses. In this case, the plural possessive form will be “glasses’.”


  • I cannot find my glasses’ case.
  • All my glasses’ cases are customized.

The same goes for the plural possessive form of “glasses” when we refer to it as a drinking container.

  • The juice glasses’ design is the same as that of the dinner set.

Plural Noun Not Ending With “s”

We can make plural words that do not end with “s” possessive as if they are singular by simply adding an apostrophe and an “s.”


  • The line to the men’s washroom was so long. 
  • The children’s concert went well.

Mass Nouns

Some nouns are uncountable and act like mass nouns when referring to them as materials — for example, glass, rice, and many others. However, mass nouns do not have any plural form, so they function as singular in the possessive form. This article was written for


  • Glass’s properties.
  • Glass’s melting point.

Final Thoughts

Always be aware of the punctuation rules for the particular style your audience is most likely to accept, but academic style guides only accept  “glass’s” as the singular possessive form of the noun “glass.” 

Understanding how “glass” functions in a sentence and the various meanings it may have will help you determine if you can use it in the singular or plural possessive form.

Just remember, “glass” does not have a plural form when you refer to it as a material. But when referring to more than one drinking container or spectacles, its plural form is “glasses’” and not “glass’.” The possessive form can appear challenging, but it’s logical if you follow the rules.