What is a word not used in formal speech or writing?

It's impossible to give a single word that's *never* used in formal speech or writing. Language is constantly evolving, and what's considered informal today might become more acceptable tomorrow.

However, here are some examples of words and phrases generally considered informal and often avoided in formal settings:

Slang:

* "Dude"

* "Chill"

* "Awesome"

* "Totally"

* "Like" (as a filler word)

Informal language:

* "Gonna" (instead of "going to")

* "Wanna" (instead of "want to")

* "Gotta" (instead of "have to")

* "Cuz" (instead of "because")

* "Y'all" (instead of "you all")

Vulgar or offensive terms:

* These are generally unacceptable in any formal setting.

Technical jargon:

* While technical terms are sometimes used in formal speech, they should be explained or defined if not universally understood.

It's important to remember that context matters.

A word that might be considered informal in a formal presentation might be perfectly acceptable in a casual conversation with friends. The level of formality is determined by the audience and the situation.