farewell
UK /?fe??wel/ US /?fer?wel/
n. 告别，辞别；再见；再会
int. 别了！（常含有永别或不容易再见面的意思）；再会！
adj. 告别的
an acknowledgment or expression of goodwill at parting
离别时对善意的承认或表示
the act of departing politely
礼貌地离开的行为
剑桥英语词典中的解释：
an occasion when someone says goodbye:
某人说再见的场合:
例句：We said our sad farewells and got on the bus.
我们悲伤地告别后上了公交车。
例句：He bid us both a fond (= affectionate) farewell.
他深情地向我们俩道别。
done at the time someone is leaving a place or job:
当某人要离开一个地方或工作时:
a farewell speech
告别演讲
a farewell party
告别会
例句：We gave Latoya a farewell party on her last day.
我们在拉托亚最后一天为她举行了一个告别会。
dictionary.com上的解释：Interjection 感叹词
goodby; may you fare well:
再见；祝你一路顺风：
Farewell, and may we meet again in happier times.
再见了，愿我们在更幸福的日子里重逢。/再见，愿我们在更快乐的时光里再次相见。Noun 名词
an expression of good wishes at parting:
告别时表达的良好祝愿:
They made their farewells and left.
他们告别后离开了。
leave-taking; departure:
告别;离职:
a fond farewell.
依依惜别。
a party given to a person who is about to embark on a long journey, retire, leave an organization, etc.
为即将踏上长途旅行、退休、离开组.织等的人举办的聚会。Adjective 形容词
parting; valedictory; final:
离别;告别;最后:
a farewell performance.
告别演出。
vocabulary.com上写的farewell的定义：
If you’re saying goodbye to someone you might not see for long time, say farewell, preferably while waving a hankie from the Queen Mary before it sails across the Atlantic. Farewell is a fancy way to say goodbye.
A farewell is also an expression of good wishes at a parting. If you’re leaving a job after being there a long time, your co-workers might throw you a farewell party. Farewell is an expression, like "goodbye," but also a noun — if you like to leave without a lot of fuss, you don’t like long farewells. Farewell is a combination of fare and well. Fare comes from the Old English word faran, which means "to journey."
大概意思是：
如果你要和一个你可能很长时间都见不到的人道别，farewell是一种别致的告别方式。
farewell也是离别时表达美好祝愿的一种方式。一份干了很久的工作要离职时，你的同事可能会为你举办一个告别会/欢送会（farewell party）。Farewell是fare和well的结合。Fare来自古英语单词faran，意思是“旅行”。
找到很多版本，仅供参考。goodbye更口语化，farewell更正式farewell 常含有不容易再见面的意思，在书面中有些文学性的表达，如“永别”等的意思。farewell常含“永别了”的意思百，可能今后都不会再见。goodbye就是普度通的再见，一种礼貌用词。farewell比较正式，往往用在书面上，不过现在口语中说也常常带有玩笑的味道，比如“ farewells guys ”, 大家再见喽。goodbye只是很普通的再见，通常不用在正式书面上。知乎上有个人说：Farewell只有在同事离职的时候会用到，而且也不会藱n隹冢ǔＪ槊嫜牖嵝�"farewell party"不会有人真的张嘴跟你说"farewell"。
以下是离职前一封正式而精简的Farewell Email例子：（收藏备用）
Dear all,
如果想用亲切点的语气，可以用：
Dear colleagues and friends,
Content 內文
As you may have heard, I am bidding adieu to _______ Company.
你或已知悉，我将要离开_______公司。
I would like to take this chance to thank you all for your support and guidance these years.
我想借此机会，感谢你们这些年来的支持与指导。
I cherish all the valuable experience that I have gained and it’s been a great time here working with you.
我很珍惜与你们啦事所获得的宝贵经验。
Keep in Touch 保持联系
「今日留一线，日后好相见。」离开不代表从此断绝来往，毕竟在职场上，说不定某天有机会再共事。可以的话，不妨留下私人电邮和电话号码作日后联络，表现出你是一个重视关系的人，亦能告诉「旧同事」即使离开也能做朋友。
It might be my last day here, but we can still keep in touch.
今天是我在公司的最后一天，但我们仍可保持联络。
You may contact me at _______ or by phone at _______, so don’t hesitate to reach out whenever.
你随时可以用电邮或电话联系我。
Complimentary Close 结束语
I wish you all the best in the future.
祝大家一切順利。
或
Thanks again and wish you all the best in the coming years.
再次感谢大家，祝你们来年一切顺利。
或
It has been a pleasure working with you and I wish you all the very best.
能与各位共事是我的荣幸，祝福你们。
最后附上几张farewell quotes（告别语）的图片：