malaria [M18th] Before people understood that malaria was transmitted by mosquitoes, they attributed the disease to an unwholesome condition of the atmosphere in marshy districts. It was particularly prevalent in Italy, and especially near Rome. In a letter of 1740 the writer and statesman Horace Walpole wrote of ‘A horrid thing called the mal’aria, that comes to Rome every summer and kills one’. Italian mal’aria is a contraction of mala aria ‘bad air’. Malady [ME] comes from a similar source, being from Lain male ‘ill’ and habitus ‘having (as a condition)’.