historical linguistics
introduction
Historical Linguistics is, quite frankly, a monster of a field. It encompasses every single other field of linguistics and looks at it from a historical perspective to see how languages have evolved over time. This means looking at how phonology, morphology, and syntax in languages has changed over time - just to name a few! This means that by nature, Historical Linguistics is a very research-intensive field.
It is through Historical Linguistics that we've learned about the different changes in English from Old English to Middle English to the Modern English that we speak today. Old English itself was very different to our Modern English in that few of the words are recognizable and there are even unfamiliar letters in it that we no longer use. However, with special study, you can understand Old English and you can even see the different changes that occurred for Old English to become the language that it is today.
We're going to go (very) briefly over some of the basic changes in English from a Phonological, Morphological, and Semantic perspective.
Phonological change
Phonological change in Historical Linguistics is jam-packed with terms and definitions to refer to the ways that sounds have changed in a language. One of the changes that I'll bring up here is the phenomenon of metathesis. Metathesis is the process of changing the sound segments in a word, usually segments that are right next to each other.
A case of metathesis in English that we are currently witnessing is the word "ask," which is being changed to "aks," especially in AAVE. What you'll be interested to hear is that the original word "ask" was actually "aks"! This debate between "ask" and "aks" has been going on since Old English and the debate continues to this day.
Morphological Change
Morphological change is prevalent among languages, especially because languages borrow from each other all of the time. With all of this borrowing going on, there is bound to be changes brought to the language. In fact, the contact that Old English had with both Old Norse and French changed the language forever. (The plural pronoun "they" that we have in English? We borrowed that from Old Norse!)
When languages do borrow from one another, they usually only borrow one word from another language. This leads to the word - despite being from another language - being subject to the borrower language's grammatical rules. The process of invoking patterns already established in your language is referred to as analogy. This happens a lot in English, a language that has borrowed quite a few words from quite a few different sources (Old Norse, French, Latin, Greek, Arabic, etc.).
One of the challenges then with having a borrowed word is to apply the analogies to it. A case of this is a common debate among English speakers: "what is the plural of 'octopus'?" A lot of people will say that "octopuses" is incorrect and that the correct version is actually "octopi." However, this method of creating plurals is from Latin and guess what, "octopus" is actually a Greek word! This means that the proper plural of the word "octopus" - according to Greek plural rules - is "octopodes." Almost no one will say octopodes, however, and therefore "octopi" is becoming the common form to refer to more than one octopus. Thus, octopi is now a new word in the English language, borrowed from the Greek word "octopus", and using Latin plural rules. Pretty cool, huh?
Semantic Change
Semantic change, or the meanings of words changing, is an obvious and natural process in language. There are many, many words in all languages that have changed meaning over time. Two types of semantic changes are referred to as generalization and specialization.
Generalization refers to a word that once had a specific meaning now having a generalized meaning. An example of this is the word "girl", which used to mean a "young person" but now specifically refers to a young female person.
Specialization then, refers to a word that was once general and has now become specific. An example of this is "hound" which used to mean "dog." Nowadays, it refers to a hunting dog only and the word "dog" has taken its place (meaning the word "dog" was generalized).
Another example of semantic change is melioration and pejoration. Melioration is an "improvement" in meaning, while pejoration is the opposite. An example of melioration are the words "queen" and "knight" which originally referred to a "woman" and a "boy" respectively, while now they refer to people in exalted positions. In contrast, the word "mistress" used to simply refer to a woman, while nowadays its definition has shifted to a woman that a man keeps for extramarital affairs. This word has therefore undergone pejoration.
Information on page from Trask's Historical Linguistics by Robert McColl Millar, p. 36-37, 62