Why is the word abbreviation such a big word?

Answer 1

To illustrate its meaning with irony.

The English language is built on many Latin words and derivatives. "Ab-" as a prefix means "to take away". In this case, you're taking away some letters to make a shortened, formalized version that can stand for a certain word. In some cases, we take away numbers, such as "I graduated in the Class of '88."

Abbreviations have rules in how they are formed. We can't just take away letters that we want to take; we only remove the letters that result in the standard abbreviation, one that's often been used and recognized over centuries.

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Etymology is from the Latin verb Abbreviare which means to make something brief. As you are shortening a word/phrase, abbreviation fits and will have to be used until another is coined.