As an expert in the field of linguistics and English language usage, I can provide a detailed explanation on the use of the word "trousers" and its grammatical form.
The term "trousers" is an interesting case in English grammar because it is a collective noun that refers to a pair of pants. In English, there are certain nouns that are inherently plural, even though they might seem singular at first glance. "Trousers" is one of these nouns, and it is always used in the plural form, even when referring to a single pair.

The reason for this is that trousers are made up of two separate parts that are joined together, forming a single garment. This is similar to other nouns like "scissors," "glasses," and "pants," which are also inherently plural because they describe items that are made up of two parts. When you refer to a single pair of trousers, you would still use the plural form "trousers," not the singular "trouser."

It's important to note that while "trousers" is plural, it is often used with the word "pair" to specify the quantity. For example, you might say, "I bought a pair of trousers," even though "trousers" is already plural. This is a common construction in English and helps to clarify the number of items being discussed.

In contrast, there is no singular form "trouser" used to refer to one part of the garment. If you were to refer to one leg of the trousers, you would simply say "a leg of the trousers," not "a trouser."

The usage of "trousers" as a plural noun is a reflection of the way English has evolved over time. Language is a living, breathing entity that changes with cultural and societal shifts. As such, certain words and their uses can become standardized through common usage, even if they don't strictly adhere to traditional grammatical rules.

In summary, "trousers" is a plural noun that refers to a pair of pants. It is always used in the plural form, and there is no singular form "trouser." When referring to a single pair, it is common to use the phrase "a pair of trousers" to specify the quantity. Understanding the nuances of such words is an important part of mastering the English language and being able to communicate effectively.

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So, there is no trouser and it's only trousers. ... A few words, though singular in nature, are made of paired items and generally treated as plural: scissors, pants, trousers, glasses, pliers, tongs, tweezers, and the like. Many are often used with the word pair as in pair of pants or pair of scissors.read more >>