periscope

名词 periscope:

1. an optical instrument that provides a view of an otherwise obstructed field

per.i.scope

n.（名词）
Any of various tubular optical instruments that contain reflecting elements, such as mirrors and prisms, to permit observation from a position displaced from a direct line of sight.
潜望镜：一种管状镜，包含折射物，如镜子和棱镜，用以观察与视线不在同一直线上的位置

【引伸】
per.iscop.ic