E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
in Latin, means an apple; and malus, mala, malum means evil. Southey, in his Commonplace Book, quotes a witty etymon given by Nicolson and Burn, making the noun derived from the adjective, in allusion, I suppose, to the apple eaten by Eve. Of course, mlum (an apple) is the Greek mlon or mlon (an apple-tree).