Have you ever experienced textpectation? According to the Urban Dictionary, that's "the anticipation one feels when waiting for a response to a text message." This new word, textpectation, is an example of a blend or (in Lewis Carroll's more fanciful phrase) a portmanteau word. Blending is just one of the many ways that new words enter the English language, and more new words are being invented constantly!
The English language has developed over centuries, and many of the words we use today have come about from one of two overarching sources: evolving words from English or English-adjacent languages themselves, or deriving from loan words from other languages. Some of those adapted words, called cognates, still sound similar to the words in other languages that they're related to, but this isn't always the case - false cognates, or words that sounds like they should be related in meaning but actually aren't, can trip up even expert writers.
In fact, most new words are actually old words in different forms or with fresh functions. We often think about word formation as something that happened centuries ago, but in fact, it's something that continues to this day. Language is constantly evolving and expanding! As some words fall out of fashion and into obscurity, others come into being, often because of highly specific contexts of time and place. This process of fashioning new words out of old ones is called derivation - and here are six of the most common types of word formation:
Over half of the words in our language have been formed by adding prefixes and suffixes to root words. Recent coinages of this type include semi-celebrity, subprime, awesomeness, and Facebookable.
From a logical perspective, affixation is probably the type of new work formation that is easiest to figure out or to use to "create" new words in casual speech. It relies on the fact that these suffixes or prefixes have known, stable definitions, so they can be attached to any existing word to layer their meaning. Affixation may create "official", formal words as well as slang.
Reversing the process of affixation, a back-formation creates a new word by removing an affix from an already existing word, for example liaise from liaison and enthuse from enthusiasm. The logic of forming these words often follows established patterns of grammar and word structure, making them fairly predictable in their creation.
A blend or a portmanteau word is formed by merging the sounds and meanings of two or more other words. Examples might include Frankenfood (a combination of Frankenstein and food), pixel (picture and element), staycation (stay and vacation), and Viagravation (Viagra and aggravation).
In many (though not all) cases, words that are created via blending are slang words with a certain element of tongue-in-cheek playfulness. In the case of words like staycation, they may even combine two words with seemingly opposing meanings. They may also involve puns or other wordplay (for instance, Frankenfood makes play on words by stitching two words together, just like Frankenstein's monster is stitched together from separate parts).
Clippings are shortened forms of words, such as blog (short for web log), zoo (from zoological garden), and flu (from influenza). In many instances, these clipped words will overtake their words of origin in popular usage, to the point where the original words or phrases become obsolete. No one calls a blog a "web log" anymore, and although "influenza" is still a valid medical term, common parlance is to simply call that particular family of viruses "the flu."
A compound is a fresh word or expression made up of two or more independent words: office ghost, tramp stamp, breakup buddy, backseat driver. Phrases like these will create a new, specific image separate from their individual parts, often with highly specific connotations or figurative language. A "backseat driver," for instance, refers to a person who tries to direct or advise the driver of a vehicle, often to an annoying degree, figuratively "driving" from the back seat.
By this process (also known as functional shift), new words are formed by changing the grammatical functions of old words, such as turning nouns into verbs (or verbing): accessorize, party, gaslight. Much like back formation, the formation of these words tends to emphasize known grammatical conventions.