The plural of sheep is sheep.
A sheep is a domesticated, wooly mammal of the Ovis family. They are ruminant, herbivorous mammals.
The word "sheep" is an irregular plural noun, which means that it does not follow the usual patterns for forming plurals in English.
The plural form of "sheep" is one of the few nouns whose plural form is the same as the singular form.
This is in contrast to regular plural nouns, which form the plural by adding an "s" to the end of the singular form, as in "dog" becoming "dogs" or "cat" becoming "cats."
There is no specific reason why the plural form of "sheep" is "sheep."
It is simply the way that the word has evolved over time, and it is a common pattern among many other English nouns, such as "deer," "moose," "swine," and "bison."
The word "sheep" as a singular and plural noun comes from the Old English sceap, which is of Germanic origin.
The word has been used in English to refer to the domesticated ruminant animal that is raised for its wool and meat since the 9th century.
Here are a few examples that illustrate the use of "sheep" in the singular and plural forms:
Singular: "I saw a lone sheep in the field."
Plural: "I saw several sheep in the field."
Singular: "The sheep is a domesticated animal that is raised for its wool and meat."
Plural: "Sheep are known for their docile nature and their ability to survive in harsh environments."
The graph shows the occurances of the plural of sheep in written English since 1800 using Google's Ngram Viewer.
Unlike wild sheep, their domestic counterparts do not stop growing hair once it is already long. It continues to grow until cut!
Sources:
https://modernfarmer.com/2017/12/6-facts-sheep-might-not-know