threshold
/ˈθreʃhəʊld/noun
1
- a strip of wood or stone forming the bottom of a doorway and crossed in entering a house or room门槛; 门口。
1.1
- in sing. a point of entry or beginning入门; 开端; 开始：
she was on the threshold of a dazzling career.
她正要开始灿烂的职业前程。
1.2
- the beginning of an airport runway on which an aircraft is attempting to land机场跑道入口; 跑道头。
2
- the magnitude or intensity that must be exceeded for a certain reaction, phenomenon, result, or condition to occur or be manifested临界点, 阈值。
2.1
- the maximum level of radiation or a concentration of a substance considered to be acceptable or safe（物质辐射或浓度的）安全阈值。
2.2
- Physiology & Psychology a limit below which a stimulus causes no reaction【生理, 心理】阈, 限, 界限, 临界：
everyone has a different pain threshold.
每个人的痛觉阈不同。
2.3
- chiefly Brit. a level, rate, or amount at which something such as a tax comes into effect〈主英〉起始点; （税的）起征点：
the VAT threshold.
增值税起征点。
词源
Old English therscold, threscold; related to German dialect Drischaufel; the first element is related to THRESH （in a Germanic sense 'tread'）， but the origin of the second element is unknown.