* Letter Frequency: Some letters are used much more often than others. For example, "E" is the most common letter, while "Z" and "Q" are quite rare. It's unlikely to find a word that uses all of them.
* Word Formation: English words are formed based on rules of pronunciation and meaning. It's extremely difficult to create a real word that includes all the letters without sounding nonsensical.
Here's a fun alternative:
You could create a phrase that uses all the letters, like this:
* "The quick brown fox jumps over a lazy dog."
This is a classic pangram – a sentence that uses all the letters of the alphabet.