1.companion的基本意思是“同伴”“伙伴”,指共同度过闲暇时建立起来的友谊联系并相伴的人或动物,也可指与另一人共事、同甘共苦的人或有共同兴趣、爱好的人,引申也可指成双、成对或成套的物品之一。
2.当表示“(某人)…的同伴”时,常用介词for或to。

a companion for
(某人)的同伴 partner of sb
The little girl will be a companion for my small daughter.那小女孩将作我小女儿的同伴。
He's not much of a companion for me.他和我不大合得来。

a companion to
1.(某人)的同伴 partner of sb
She became a companion to a foreigner.她成为一个外国人的同伴。
I worked as a companion to an old princess.我曾给一位老公爵夫人当过陪伴。
2.能与…相匹配的东西 matchable sth
I used to have a companion to that ornament, but I broke it.我原来还有一件装饰品和那一个配对,可是我把它弄坏了。
That book forms a companion to the present volume.那本书与现有的一册成为姐妹篇。

Both my travelling companion and I wanted to go to Waterloo—that historic battlefield.我的旅游伙伴和我都想去滑铁卢——那个历史上著名的战场。
He was perverted by his evil companions.他被坏伙伴引入歧途。
The seeing eye dog was the blind man's constant companion.导盲犬是盲人的忠实伙伴。
A dictionary is his constant companion.词典是他忠诚的伙伴。
She looked around for her probable companions.她环顾四周寻找可能的同伴。
They were working companions.他们是同事。
The companion volume will soon be published.这卷书的姊妹篇即将问世。

companion, associate, company, comrade
这组词都可表示“同事”“同伴”“朋友”。其区别是:associate指由于共同的职业、地位、利益而经常联系的人; companion强调共同度过闲暇时建立起来的友谊联系; company主要指想法相似,但没有深交的“同伴”“朋友”; comrade指与某人在观点或事业上有一致性和利害关系的“战友”或“同志”。例如:
He is not a friend but a merely business associate.
他不是朋友,只是一个生意伙伴而已。
My fellow travellers made good companions.
我和与我一起旅游的人成了好伙伴。
The teacher advised his pupils always to keep good company.
老师建议学生要交好朋友。
The soldier stayed with his wounded com-rade.
那位战士和他受伤的战友留了下来。

［同义词］   associate, colleague, comrade, friend, mate, partner
［词源］  ＜晚期拉丁语compaio (同另一人一起分享面包的人)