a.

1. 附有条件的，以……为条件的[（+on/upon）]
   The sale of the painting was conditional on the expert's agreement that it was an original Rembrandt.

   这幅画的出售须要有专家认可它确是伦勃朗的原作才行。

2. 【语】表示条件的
   "If we go" is a conditional clause.

   “要是我们去的话”是条件句。

3. 【逻】有条件的

n.

1. 【语】条件句；条件语[C]

adj.

1. subject to one or more conditions being met.
2. Grammar  expressing a condition.

n.

1. Grammar  & Philosophy  a conditional clause or conjunction.
2. Grammar  the conditional mood of a verb, for example should in if I should die.