What is an "acronym"?

An acronym is indeed a type of abbreviation that is formed by taking the first letters of each word in a phrase and combining them to create a new word. This allows for easier communication and memorization, especially with lengthy terms or organizations. An example of this is "NASA," which stands for the National Aeronautics and Space Administration.

The other options describe concepts that do not accurately represent what an acronym is. A long form of a word pertains to a different concept related to the extension of a word rather than a condensed form. A method of analyzing words suggests a process of breaking down or understanding words in a different context, which does not apply to the creation of acronyms. Lastly, a form of poetic expression refers to literary forms and structures, which is unrelated to the formation and use of abbreviations. Thus, the definition of an acronym as a type of abbreviation formed from the first letters of each word is the correct understanding.