[m_for_monkey]

Interestingly, while humor/humour is a US/British difference, humorous/humourous is not, the latter is just rare/unusual.

https://en.wiktionary.org/wiki/humour

https://en.wiktionary.org/wiki/humourous

[benjoffe]

Ah I see, thanks, there are certainly better examples though, after a few minutes I found 'unshakeable'* which google tries to correct to the American version, yet is standard British English.

* https://www.google.co.uk/search?q=unshakeable (even makes the mistake on the UK Google site).

[waqf]

> rare/unusual

Or "misspelt/misspelled", as we prescriptivists like to call it.

Though when I see hypercorrections like "humourous" on the internet, I begin to suspect that people are using UK/Commonwealth spellings because they think they should, not because they're actually more familiar with those spelling conventions.