From Longman Dictionary of Contemporary Englishdiaristdi‧a‧rist /ˈdaɪərɪst $ ˈdaɪr-/ noun [countable] TCNsomeone who writes a diary, especially one that is later sold
Examples from the Corpus
diarist• To Baddiel it was solipsistic and showed the limits of a diarist.• Some have later called this traveler and diarist a saint, and saints are not necessarily representative of their sets.• Elderly diarists were rare, and younger diarists not much concerned with observing the old.• Never heard of him, one of those embarrassing admissions the best of diarists have to make at times.• He was also a meticulous parliamentary diarist, providing the fullest known account of debates in 1626,1628, and 1629.• Nor should we forget our latter-day Darwin: the diarist, novelist or would-be intellectual sitting at home with his word-processor. 