Is there an English word with three suffixes?

It's tricky to find a word with three suffixes in the *strict* sense of the word, as suffixes are typically added to the end of a word. However, we can get close:

* "Unbelievable-ness"

* This word uses the prefix "un-", the suffix "-able", and then the suffix "-ness". While "un-" is a prefix, it's essentially acting like a negative suffix in this case, modifying the meaning of the root word.

* "Nationalization"

* This word uses the suffix "-al" to create "national", then the suffix "-ize" to create "nationalize", and finally the suffix "-ation" to form "nationalization".

Therefore, while you won't find a word with three *true* suffixes, there are words that use a combination of prefixes and suffixes to achieve a similar effect.