She extinguished the desk lamp, and the room immediately became dark.

extinguished 是动词 extinguish 的过去式。extinguish 由前缀 ex-（表示"向外"）和词根 stinguere（拉丁语，意为"熄灭"）组成，字面意思是"使火向外熄灭"，引申为"熄灭、关闭（灯光等）"。