The police conducted a three-night stakeout near the bank and finally caught the robber.

stakeout 是由动词短语 stake out 合并而成的名词。stake 原指"木桩"，引申为"监视点"；out 表示"在外"。stakeout 指警方"在外设点监视"的行动，即"蹲守"或"监视行动"。