kindly give me examples of formal terms in language and informal terms in language
Remember that most words exist in many different registers. Every language genre uses common prepositions, adjectives, verbs, nouns, etc.
Formal language tends to use a more extensive vocabulary and a more complex sentence structure. You may run into words such as: albeit, thus, and many polysyllabic words, such as quintessential and polymorphism.
Very informal language is often not sentence based, but phrase based. It may contain simple words, slang, and shortenings (donthcha, couldya, gonna, etc.) and now, with the explosion of chat rooms and text messaging, a lot of abbreviations (c U l8er).
As one progresses to more formal language, sentences return and the vocabulary moves towards a more standard form.
What precisely did you want to know?
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