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

悪循環[akujunkan] vicious circle
一環[ikkan] link (e.g. a part of a larger plan)
印環[inkan] signet ring (in medical contexts, e.g. signet ring cell)
円環[enkan] circle
花環[hanawa] wreath

環境[kankyou] environment
環境グループ[kankyouguruupu] environmental group
環境事業[kankyoujigyou] environmental business
環境庁[kankyouchou] Environment Agency
環境庁長官[kankyouchouchoukan] Director General of Environment Agency