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)

ランブル鞭毛虫[ranburubenmouchuu] giardia (flagellate protozoan)
ランブル鞭毛虫症[ranburubenmouchuushou] giardiasis
いも虫[imomushi] hornworm (caterpillar of a hawk moth)
益虫[ekichuu] useful insect
円虫類[enchuurui] round worms

夏虫[natsumushi] summer insect
蛔虫[kaichuu] roundworm (Ascaris lumbricoides)
害虫[gaichuu] harmful insect
鈎虫[kouchuu] hookworm
寄生虫[kiseichuu] parasite