か弱い[kayowai] frail
ひ弱い[hiyowai] weak
意志薄弱[ishihakujaku] weak-willed
胃弱[ijaku] dyspepsia
虚弱[kyojaku] feebleness

強弱[kyoujaku] strength
弱い[yowai] weak
弱い者[yowaimono] weak person
弱い相互作用[yowaisougosayou] weak interaction (physics)

悪怯れる[warubireru] to be timid
怯える[obieru] to become frightened
怯む[hirumu] to falter
卑怯[hikyou] cowardice
卑怯者[hikyoumono] coward

怯懦[kyouda] cowardice
卑怯千万[hikyousenban] very mean (sneaky)
怯え[obie] being startled, surprised or afraid
怯弱[kyoujaku] coward