Klein bottle 克莱因瓶
*拓扑学(topology)中无边的单面圆柱面。以下述方法粘合：把渐细的试管的小端穿过试管的一面，展开并同大端联结。由德国数学家克里斯蒂·费利克斯·克莱因(1849—1925)发明。
克莱因瓶 无边而只有一面的实体。
- National Trust
- National Vocational Qualifications
- Nation of Islam
- Nations and Works Agency for Palestine Refugees in the Near East
- Nations Educational，Scientific and Cultural Organization
- Nations High Commissioner for Refugees，Office of the
- Natron，Lake
- natterjack
- natural gas
- Natural History Museum
- Naturalism
- naturalization
- natural selection
- Nature Conservancy Council
- Naukratis
- Nauplia
- Nauru，Republic of
- Nausicaa
- nautical mile
- nautilus
- Navajo
- Navarino，Battleof
- Navarre
- navel
- navigation