Origins
Something slight was once something smooth.βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ The word comes from Old Norse slΓ©ttr, meaning 'flat, level, even', from Proto-Germanic *slihtaz. In 13th-century English, slight described surfaces: a slight field was a smooth one, without bumps or features.
The semantic journey from 'smooth' to 'small' followed a chain of associations. A smooth surface is a plain surface. A plain thing is an unremarkable thing. An unremarkable thing is a trivial thing. By the 15th century, slight meant 'small' or 'insignificant', and the smooth surface had been forgotten.
The verb arrived in the 16th century, completing the transformation. To slight someone was to treat them as smooth β as flat, featureless, beneath your notice. A slight became an insult delivered not through aggression but through indifference.
Later History
German schlicht preserves the older sense with remarkable clarity. Schlicht means 'plain, simple, modest' β still carrying the original idea of smoothness without pretension. A schlichte Eleganz ('plain elegance') in German would be a contradiction in English, where slight now implies deficiency rather than refinement.
The word sleight (as in sleight of hand) is a false friend β it comes from a different Old Norse word, slΕgΓ°, meaning 'cunning'. Spelling deceives; the two words are strangers.