sprækur (comparative sprækari, superlative sprækastur)
From Old Norse sprækr (“nimble, lively”) from Proto-Germanic *sprēkiz (“lively”), from Proto-Indo-European *(s)pereg- (“to strew, jerk, sprinkle, scatter”). Cognates include English spry, sprey, Swedish dialectal sprygg (“brisk, very active, skittish”).