"Sleekit" is one of Burns's most memorable words, appearing in the famous address "To a Mouse" where the creature is "wee, sleekit, cowrin, tim'rous." It describes both physical sleekness and the moral smoothness of cunning and deceit, the two senses reinforcing each other perfectly. In Scots verse it is a powerful term of mild condemnation or amused recognition, applied to the politically evasive, the socially calculating, or the merely cunning. Its double meaning makes it exceptionally rich for satirical purposes.

Sleekit is most famous from Burns's "To a Mouse" — "Wee, sleekit, cowrin, tim'rous beastie" — where it describes the smooth coat of the mouse. But its more common meaning, sly and untrustworthy, adds a layer of irony to Burns's address: is the mouse truly sleekit in the moral sense, crafty and deceitful, or is its "sleekitness" merely physical? This ambiguity is characteristic of Burns's complexity. In general Scots usage, "sleekit" is a term of moral disapproval — the sleekit person operates through flattery, smooth words, and concealed intentions. For students, the contrast between the word's literal (smooth-coated) and figurative (sly) meanings is an important example of how Scots poetry generates meaning through lexical ambiguity.