断トツ[dantotsu] the best
一刀両断[ittouryoudan] cutting in two with a single stroke
引っ張り剪断強度[hipparisendankyoudo] peel strength (conductor from substrate)
英断[eidan] resolution
横断[oudan] crossing

横断歩道[oudanhodou] pedestrian crossing
果断[kadan] decisive
間断[kandan] break in time
強制中断[kyouseichuudan] forcing to a stop
禁断[kindan] prohibition

逸速く[ichihayaku] promptly
音速[onsoku] speed of sound
加速[kasoku] acceleration
加速運動[kasokuundou] accelerated motion
加速度[kasokudo] acceleration

快速[kaisoku] high speed
快速電車[kaisokudensha] high-speed train
角速度[kakusokudo] angular velocity
急速[kyuusoku] rapid (e.g. progress)
減速[gensoku] deceleration