アナログデジタル変換器[anarogudejitaruhenkanki] analog-digital converter
圧搾器[assakuki] compression
圧力調整器[atsuryokuchouseiki] pressure regulator
安全器[anzenki] safety device
安定器[anteiki] stabilizer

医療器械[iryoukikai] medical appliances
育雛器[ikusuuki] breeder
化学兵器[kagakuheiki] chemical weapons
化学兵器禁止条約[kagakuheikikinshijouyaku] chemical weapons ban treaty
加減抵抗器[kagenteikouki] rheostat

懐旧[kaikyuu] recalling the old days
旧ソ連[kyuusoren] former Soviet Union
旧悪[kyuuaku] past misdeeds
旧衣[kyuui] worn-out clothes
旧詠[kyuuei] ancient poems

旧怨[kyuuen] old grudge
旧縁[kyuuen] old relationship
旧恩[kyuuon] old favors
旧仮名遣[kyuukanazukai] former (i.e. before the post-WWII reforms) kana usage in writing the readings of kanji

圧し石[oshiishi] stone weight
一石[isseki] one game (of go)
一石二鳥[issekinichou] killing two birds with one stone
英国石油[eikokusekiyu] British Petroleum
下石[shitaishi] nether millstone

化粧石鹸[keshousekken] toilet soap
化石[kaseki] fossil
化石学[kasekigaku] paleontology
化石層[kasekisou] fossil bed
化石燃料[kasekinenryou] fossil fuel