periscope

n. 潜望镜

peri-, perigee, perihelion, peril, perilous, perimeter, period, period piece, periodic, periodic table, periodical, periodicity, peripatetic, peripatetically, peripheral, peripherally, periphery, periphrasis, periphrastic, periphrastically, periscopic, perish, perishable, perishables, perished, perisher, perishing, peristyle, peritonitis, periwinkle, perjure, perjurer, perjury, perk, perkily, perkiness, perky, perm, permafrost, permanence,