ilk: [OE] Historically ilk means simply ‘same’. Its Old English form was ilca, which was ultimately a compound made up of the demonstrative particle *i- ‘that (same)’ and *līk- ‘form’ (as in the English verb like). It had virtually died out by the mid-16th century as a straight synonym for same, but one context in which it survived, particularly in Scottish English, was in the increasingly fossilized phrase of that ilk ‘of the same’, which was used originally to express the notion that someone’s name was the same as that of the place they came from: thus Nairn of that ilk would have signified ‘someone called Nairn from a place called Nairn’.
In due course it came to be applied specifically to landed Scottish families, and so strong did the connection with ‘family’ become that by the 19th century we see the first signs of ilk being treated as if it were a noun, meaning ‘family’. That led on in time to an even more general sense ‘type, sort’, capable of use in such expressions as ‘of a different ilk’.
