遺失[ishitsu] loss
遺失物[ishitsubutsu] lost article
一失[isshitsu] disadvantage (defect, error)
一得一失[ittokuisshitsu] gaining some and losing some
栄養失調[eiyoushicchou] malnutrition

過失[kashitsu] error
見失う[miushinau] to lose sight of
失う[ushinau] to lose
失する[shissuru] to lose
失せる[useru] to disappear

悔い[kui] regret
悔いる[kuiru] to regret
悔改める[kuiaratameru] to repent
悔しさ[kuyashisa] chagrin
悔泣[kuyashinaki] crying from vexation

悔み状[kuyamijou] letter of condolence
悔む[kuyamu] to mourn
悔悟[kaigo] remorse
悔恨[kaikon] regret
後悔[koukai] regret

テロ対策[terotaisaku] anti-terrorist
マーケティング策略[maaketingusakuryaku] marketing tactic
リストラ策[risutorasaku] restructuring scheme
悪策[akusaku] poor policy
安全対策[anzentaisaku] safety measure

一策[issaku] idea
下策[gesaku] poor plan
劃策[kakusaku] plan
解決策[kaiketsusaku] solution
奇策[kisaku] clever scheme