Pneumonoultramicroscopicsilicovolcanoconiosis – is a pretty impressive word.  It is a form of Silicosis – a lung disorder – caused by volcanic ash. Apparently it was coined by a Mr Everett B Smith in 1935, unsurprisingly he enjoyed puzzles.

It would seem most of the longest words are technical, well except Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch which is a lovely little place in Wales. The name means “St Mary’s church in the hollow of the white hazel near to the fierce whirlpool and the church of St Tysilio of the red cave.”