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)

脆い[moroi] brittle
脆性[zeisei] brittleness
脆弱性[zeijakusei] vulnerability
涙脆い[namidamoroi] easily moved to tears

脆弱[zeijaku] frail
情に脆い[jounimoroi] soft-hearted
脆化[zeika] embrittlement
水素脆化[suisozeika] hydrogen embrittlement