You use relative to say that something is true to a certain degree, especially when compared with other things of the same kind.
comparative
The fighting resumed after a period of relative calm.
战斗在一段相对的平静之后重新打响。
It is a cancer that can be cured with relative ease.
这是种相对来说比较容易治愈的癌症。
You use relative when you are comparing the quality or size of two things.
They chatted about the relative merits of London and Paris as places to live.
他们闲聊伦敦与巴黎作为居住地各自相对的优点。
I reflected on the relative importance of education in 50 countries.
我思考了教育在50个国家中的相对重要性。
If you say that something is relative, you mean that it needs to be considered and judged in relation to other things.
Fitness is relative; one must always ask 'Fit for what?'
“适合”是相对的;应该常常问一问:“适合什么?”
relatives
Your relatives are the members of your family.
Get a relative to look after the children.
找个亲戚来照看这些孩子。
We need to inform his relatives.
我们需要通知他的亲属。
I was taken in by my mother's only relative.
我被母亲唯一的亲戚收留了。
a counselling service for relatives and friends as well as the drug abusers themselves.
一种向滥用药物者本人及其亲友提供的咨询服务。
If one animal, plant, language, or invention is a relative of another, they have both developed from the same type of animal, plant, language, or invention.
The pheasant is a close relative of the guinea hen.
雉鸡和珍珠鸡是亲缘物种。
relative to
Relative to something means with reference to it or in comparison with it.
in relation to
Japanese interest rates rose relative to America's.
与美国相比,日本的利率有所上升。
House prices now look cheap relative to earnings.
相对收入而言,房价看起来比较便宜。
The satellite remains in one spot relative to the earth's surface.
相对地球表面而言,这颗卫星位置很固定。