1. (形状、设计或结构的)对称，匀称
    Something that has symmetry is symmetrical in shape, design, or structure.

symmetry的翻译

    e.g. ...the incredible beauty and symmetry of a snowflake...
           雪花难以置信的美丽和对称
    e.g. I loved the house because it had perfect symmetry...
           我喜欢这所房子，因为它非常对称。

2. (数量的)相等，相当
    Symmetry in a relationship or agreement is the fact of both sides giving and receiving an equal amount.

symmetry

    e.g. The superpowers pledged to maintain symmetry in their arms shipments.
           超级大国承诺在武器运输方面要保持数量均衡。

3. (国家、机构、局势的)相似,相仿
    You can refer to symmetry between countries, institutions, or situations if you think that there is a close similarity between them.

    e.g. He said that Britain would not rejoin the ERM 'until there is much greater symmetry between our economy and other European economies.'
           他说在英国经济与其他欧洲国家的经济实现更大的趋同性之前，英国不会重新加入欧洲汇率机制。