n.[C]

1. （封建时代的）诸侯；封臣
2. 从属者；下属
3. 家臣；奴仆；奴隶

a.[B]

1. 臣的；附庸的
   Wales was a vassal kingdom at that time.

   那时威尔士是个附庸国。

2. 奴仆的；奴隶的

n.

1. historical a holder of land by feudal tenure on conditions of homage and allegiance.
2. a person or country in a subordinate position to another.