The plural forms of words in English, like "houses" for "house" and "mice" for "mouse," are the result of a complex history of the English language, which includes influences from many other languages and the way words were pronounced in the past.
Regular Plural Formation: The plural of "house" follows a regular pattern in modern English where we add an "-s" or "-es" to the end of most nouns to make them plural. This pattern is a simplified system that has become the standard in English.
Old English and Middle English: The plurals "mice" and "lice" come from Old English and Middle English times when the language had more complex rules for making nouns plural, often involving changing the vowel sound in the middle of the word. This type of change is known as "i-mutation" or "umlaut," which was a common grammatical feature in the Germanic languages that English descends from.
Irregular Plural Formation: Over time, as the language evolved, most of these complex forms were regularized to the simpler "-s" or "-es" ending, but some words, like "mouse" and "louse," retained their old plural forms. These are known as irregular plurals.
Standardization and Change: English has undergone significant standardization over the centuries, and the regular "-s" or "-es" ending has become the norm due to its simplicity and regularity. However, irregular forms persist due to historical usage and the conservative nature of language when it comes to frequently used words.
Thus, "houses" is a result of linguistic simplification and standardization, while "mice" and "lice" are remnants of older linguistic patterns that have been preserved in the language.