13 letters · 18 points in Scrabble
adjective reactive or functioning or allowing movement in two usually opposite directions
originEtymology tree Proto-Indo-European *dwóh₁ Proto-Indo-European *dwi- Proto-Italic *dwi- Latin bi-bor. English bi- English direction Proto-Indo-European *h₂el-der.? Proto-Italic *-ālis Latin -ālisbor. Old French -albor. ▲ Latin -ālis Old French -elbor. ▲ Latin -ālisbor. Middle English -al English -al English directional English bidirectional From bi- + directional.
Etymology from Wiktionary, CC BY-SA 3.0