概述
上義詞是對事物的概括性、抽象性說明；下義詞是事物的具體表現形式或更為具體的說明。
個別舉例
以immigrate和emigrate以及migrate之間詞義關係為例說明如下：
immigrate: 移居入境；To enter and settle in a country or region to which one is not native.
Britain immigrated many colonists to the New World.
英國把大量殖民者移居到了新大陸
emigrate：移居出境，也就是通常說的移民（v）；To leave one country or region to settle in another.
His family emigrated to the U.S. last winter.
他們一家去年冬天移民到美國了。
migrate：移動, 移往, 移植, 隨季節而移居, (鳥類的)遷徙
After the Nazis came to power in Germany, many scientists emigrated (that is, left Germany).
納粹奪取了德國的政權之後，許多科學家都遷走了（也就是說，離開了德國）。
The promise of prosperity in the United States encouraged many people to immigrate (that is, move to the United States).
興旺發達的前景吸引了眾多的移民到美國（也就是指，遷入了美國）
immigrate和emigrate意思相反，一個是移進，一個是移出，而migrate可以說是immigrate和emigrate的上義詞。
