Adam Jack Aitken (1921–1998) wis a Scots lexicographer an a leadin scholar o the Scots leid.

Jack Aitken wis born in Edinburgh, grew up in Bonnyrigg, Midlowden, an wis eddicate at Lasswade High School. He wis the auldest o three bairns o Adam Aitken, a miner, and his first wife Alexandrina Sutherland, wha dee’d whan Jack wis aboot nine. He tholed neglect as a step-bairn, bit his meenister, Rev. Oliver Dryer, halpit him to lea hame at the age o saxteen, an he ay stuck in at the schuil thanks tae a bursary. Bein the son o a miner, he got ither bursaries that alloued him to gang tae the University o Edinburgh in 1939. He ser'd in the Ryal Artillery durin Warld War ll as a lance bombadier, an tane pairt in the Normandy landins an in the war in North Africa, risin tae the rank of sairgeant major. He wis commendit for bravery be Field-Marshall Montgomery in 1944. He graduatit MA with First Class Honours in English Language an Literature fae the Varsity o Edinburgh in 1947. In 1948 he wis appyntit Assistant tae Sir William Craigie, the Editor o The Dictionary of the Older Scottish Tongue (DOST) that is nou online as the Dictionar o the Scots Leid. He became Editor hissel whan Craigie retiret in 1956. Whan he tane ower editorial responsibeelity for DOST, Aitken pit in place a new readin programme that aboot dooblet the list of warks excerptit for the dictionar, correctin the bias taewart verse an leeterary prose. Aitken’s editor­ship begoud wi the letter J, an the impack o the new readin programme is tae the fore fae the thrid volume on.

Aitken wis ane o the first tae catch on tae the uisefuness o the computer for research in the Airts. Although computer methods kythed ower late tae be the wirkhorse o the collection process for DOST, he set up, wi ithers, the Older Scots Textual Archive, a computer-readable archive wi mair nor a million wirds o Aulder Scots leeterature. 

For the maist o his career, up tae 1979, he combint his wark on DOST wi teaching, as a Lecturer an than a Reader in the Depairtment o English Language. He can be sayed tae hae creatit ‘Scots language’ as a univairsity subjeck. The haundoots that he screivit in the 1950s for his courses on the Scots leid wis for mony a year the only clear summaries o Scots vocabular, phonology, orthogra­phy, grammar an stylistics that existit, an they circulatit widely amang scholars. Ower time he made the maist o this material available in prent, and his writins is at the founs o the subjeck.

He wis Chairman o the Language Committee of the Association for Scottish Literary Studies 1971–1976; Chairman o the Forum for Research on the Languages of Scotland 1978–1981 an Honorary President fae 1994; Vice-President o the Scottish Text Society fae 1985; Honorary Preses of the Scots Language Society fae 1994; Honorary Vice-President o the Scottish National Dictionary Association fae 1995; an Honorary Vice-President o the Robert Henryson Society fae 1996. In 1981 the British Academy awardit him the Biennial Sir Israel Gollancz Prize. In 1983 he was awardit a DLitt be the Varsity o Edinburgh, an wis appyntit Honorary Professor in 1984. In 1987, he wis presentit wi a Festschrift: The Nuttis Schell, Essays on the Scots Language presented to A J Aitken.

Aitken is weel-kent for his formulation o the Scots Vouel Lenth Rule, kent as Aitken's Law forby. He developed a nummerin seestem for the Scots vouels that alloued a better unnerstaundin an descreeption o thair historical development.

He retirt in 1986 an dee’d at hame in Edinburgh on 11 February 1998 o ischaemia.