Etymology
Uncertain. The following words, all first attested later than the headword, have been compared:
* Irish smidiríní, smiodairíní (“smithereens”), from smiodar (“broken piece, fragment”) + -ín (suffix forming diminutive nouns) + -í (slender form of -aí (suffix forming plurals of some nouns)).
* smither (“fragment; atom”), which would be suffixed with -een (forming diminutive nouns in Irish English).
* Hiberno-English (Wexford) smaddereen, a variant of smattering (“small amount or number of something; shallow or superficial knowledge of a subject”).
* Hiberno-English (Wexford) smithered, smashed