1. 保持;保留
The retention of something is the keeping of it.

1. the act of retaining something

Synonym: keepingholding

2. the power of retaining liquid

e.g. moisture retentivity of soil

Synonym: retentivenessretentivity

3. the power of retaining and recalling past experience

e.g. he had a good memory when he was younger

Synonym: memoryretentivenessretentivity