[psudmant]

"Antivenom" is not a word. This article is mistakenly using this word to refer to antivenin.

[reallydude]

It's a word that people use. Despite assertions that there are definitive word lists for languages, all words are made up over time.

https://www.merriam-webster.com/dictionary/antivenom

https://en.oxforddictionaries.com/definition/antivenom

You are free to pursue this futile fight.