1. 克制的;冷静的;不动声色的
Someone who is restrained is very calm and unemotional.

2. (穿着、装饰等)简单的，淡雅的，朴素的
If you describe someone's clothes or the decorations in a house as restrained, you mean that you like them because they are simple and not too brightly-coloured.

1. prudent

e.g. guarded optimism

Synonym: guarded

2. cool and formal in manner

Synonym: reticentunemotional

3. not showy or obtrusive

e.g. clothes in quiet good taste

Synonym: quiet

4. under restraint

5. marked by avoidance of extravagance or extremes

e.g. moderate in his demands
restrained in his response

Synonym: moderate