Noun:

1. rear gunsight having an open notch instead of a peephole or telescope

open pitadj.露天采掘的openadj.开着的；开放的；公开的v.打开；张开；展开；摊开；开始(某事物)；开张；营业；以…开头；宣布启用n.户外；公开open system interconnection reference model开放系统互连参考模型open solar absorption refrigerating machine敞开式太阳能吸收制冷机open-loop man-machine transfer function开环人-机传递函数Open Education Needs Open-minded Teachers开放教育的教师观Open tubular capillary electrochromatography开管毛细管电色谱Open Systems Interconnection Reference Model开放系统互连参考模型open-source software-development process开放式源码软件开发过程open-circuit underwater breathing apparatus开放式潜水呼吸器Open dislocation of metatarsophalangeal joint跖趾关节开放性脱位Open Union Information Technology Corporation开联信息技术有限公司