I always viewed dictionaries as a collection that formalized the definitions of words and phrases. However, I've seen that different dictionaries give different definitions for the same word, which changes the meaning of that word.

Take for example the word "sardonic":

> 
> [Merriam-Webster](https://www.merriam-webster.com/thesaurus/sardonic): marked by the use of wit that is intended to cause hurt feelings
> 
> 
> [Vocabulary.com](https://www.vocabulary.com/dictionary/sardonic): disdainfully or ironically humorous; scornful and mocking
> 
> 
> [Oxford Learner's Dictionary](https://www.oxfordlearnersdictionaries.com/us/definition/english/sardonic?q=sardonic): showing that you think that you are better than other people and do not take them seriously
> 
> 
> New Oxford American Dictionary: grimly mocking or cynical
> 
> 
> 

Some of the dictionaries seem to imply that it describes someone who is scornful because of their sharp sense of humor, while the others seem to imply it's because of arrogance. These definitions seem to clash with each other.

Which one should I focus on? Is there a "standard" dictionary that I can always rely on?