Below is a list of words that will give a Scottish novel the tone it needs without being overbearing.
1) Clan - Consists of families claiming a common ancestor and following the same hereditary chieftain, specifically in Scotland, but some clan systems exist in other Celtic countries such as Ireland and Wales. The word clan means children.
2) Clan Chief or Chieftain - Ruler of a specific clan, traditionally the heir would have to be elected. In the present-day system, the chief must be approved by The Court of the Lord Lyon (Lyon Court). Chieftains can be rulers of a branch of a clan, while a Clan Chief can be ruler of all the clan branches and ruling Chieftains. These rulers led their clans in battle, made decisions regarding disputes among clan members, etc.
3) Laird - A member of the gentry and a heritable title in Scotland, very similar to the titled, landholding lords in England. The title is granted to the owner of an estate and may hold certain local or feudal rightss, as well as voting rights in Scotland's Parliament.
4) Lass or Lassie - A young girl.
5) Lad - A young man.
6) Aye - Yes.
7) Nay - No.
8) Ken - To know. Many American southerners use a similar expression such as, I reckon it's time to retire for the night.
9) Mayhap - Perhaps.
10) Yer - Your.
11) Ye're - You are or you're.
12) Mither - Mother.
13) Da - Father.
14) Tartan - A plaid design of Scottish or Irish origin consisting of stripes of varying width and color usually patterned to designate a distinctive clan.
15) Plaid - A twilled woolen or cloth fabric with a tartan pattern worn by various Scottish clans.
16) Kilt - A knee-length skirt (although many Scots hate this term) with deep pleats, usually of a tartan wool, worn as part of the dress for men in the Scottish Highlands. Only available after the mid-1700's.
17) Great Kilt - Clothing made from wool, often grown on one's own sheep. The yarn would be taken to a local weaver for cloth, 27" wide and up to 30" wide. The first known reference to the Great Kilt was in 1594. One description is quoted as, "their exterior dress was mottled cloaks of many colours with a fringe to their shins and calves, their belts were over their loins outside their cloaks."
18) Aft - Often.
19) Bairne - Baby.
20) Loch - Lake.
21) Claymore - Large sword.
22) Daft - Mad or crazy.
23) Glen - Valley.
24) Kirk - Church.
25) Wee - Small.
26) Auld - Old.
27) Tarry - Take one's time.