Adam Jack Aitken (19 June 1921 – 11 February 1998) was a Scottish lexicographer and leading scholar of the Scots language.

Aitken was born on 19 June 1921 in Edinburgh, grew up in Bonnyrigg, Midlothian, and was educated at Lasswade High School.

He was the only son and eldest of the three children of Adam Aitken, a miner, and his first wife Alexandrina Sutherland, who died when Jack was about nine.

When he took over editorial responsibility for DOST, Aitken instituted a new reading programme that approximately doubled the list of works excerpted for the dictionary, correcting the bias towards verse and literary prose.

For most of his career, up to 1979, Aitken combined his work on DOST with teaching, as a Lecturer and latterly Reader in the Department of English Language, University of Edinburgh.