13 letters · 19 points in Scrabble
adjective (especially of fissionable material) able to sustain a chain reaction in such a manner that the rate of reaction increases
originEtymology tree Proto-Indo-European *úp Proto-Indo-European *-er Proto-Indo-European *upér Proto-Italic *super Latin super Latin super-lbor. English super- Proto-Indo-European *krey- Proto-Indo-European *krinyétider. Proto-Hellenic *kríňňō Ancient Greek κρῑ́νω (krī́nō) Ancient Greek κρῐ- (krĭ-) Proto-Hellenic *-tās Ancient Greek -τής (-tḗs) Ancient Greek κρῐτής (krĭtḗs) Proto-Indo-European *-kos…
Etymology from Wiktionary, CC BY-SA 3.0