Smidgen
A small amount, a tiny piece. 'Just a smidgen of butter on the bread' is a measured amount, smaller than 'a bit' and larger than 'a trace'. The diminutive is the point: smidgens are by definition modest.
Etymology
Likely from Irish 'smidean' (= a fragment, a small bit), itself a diminutive form. Recorded from at least the mid-nineteenth century; the Irish origin is the most-cited derivation. The Hiberno-English form then travelled into wider English; modern American English carries 'smidge' / 'smidgen' freely and most users no longer know the Irish root.
In a sentence
"Just a smidgen of milk in my coffee, thanks."
Historical notes
Smidgen is one of those Hiberno-English words that escaped into general English so thoroughly that its origin has become invisible. American baking instructions use 'a smidge' or 'a smidgen' as informal units of measurement (smaller than a pinch); British speakers use it for small portions of anything. The Irish source is still cited in dictionaries but no longer carried by speakers. The doubled diminutive logic (Irish '-ean' is already a diminutive) explains why the word feels so emphatically small.
Sources
- Oxford English Dictionary, entry smidgen n. · dictionary