Disbenefit

In some recent copy I came across the word 'disbenefit' for the first time. It sounded strange to me - my first instinct was to replace it with 'disadvantage' - but the OED had no problem with it, and Googling it displayed tens of thousands of results, so I let it stand.

Admittedly, as an exclusively British English word, 'disbenefit' may also sound strange to American ears, but that gives an Englishman such as myself no excuse.

My discovery of 'disbenefit' has made me wonder how I could go for so long without coming across such a relatively common word - and consequently, what other common words I am unaware of. Has anybody else had a similar experience?