diary: [16] Like its semantic cousin journal, a diary is literally a ‘daily’ record. It comes from Latin diarium, a derivative of diēs ‘day’. Originally in classical Latin the word meant ‘daily allowance of food or pay’, and only subsequently came to be applied to a ‘record of daily events’. From the 17th to the 19th century English also had an adjective diary, from Latin diarius, meaning ‘lasting for one day’. [diary etymology, diary origin, 英语词源]