n (1)特定时刻(particular time esp as marked by certain circumstances)[C]：on this/that/the present/the last/one～在这一时刻/在那一时刻/这次/上次/有一次;They on several～s almost took my life.有几次他们还差点要了我的命。I send my best wishes on this happy～.在这幸福的时刻，我送上最美好的祝愿。I can't recall the～，but I've met her before.我以前碰到过她，但想不起在哪个场合了。He looked round at them all and made an effort to rise to the～.他环顾他们每一个人，想努力应付好这个局面。It is considered too informal an attitude for such an～.人们认为，在这样的场合采取这种态度是过于随便了。have a sense of～有场合感;

(2)(时)机，机会(opportunity)[C，sing][N(for)]：I want to take/use this～to thank you.我想利用这个机会来感谢你。Christmas is always an～for merry-making.圣诞节始终是欢庆的时刻。This is not an～for lazy walks/laughter/tears.这不是漫步/开怀大笑/痛哭流涕的时候。If the～presents itself，I shall speak to him.如果有机会，我会跟他讲。He never missed any～of visiting the castle.他从来不错过游览这座城堡的机会。〖同〗 opportunity，chance，instance，circumstance;

(3)特殊事件，盛事(会，举)(special event or celebration)[C]：The country's bicentennial was quite an～.该国建国200周年纪念相当隆重。Let's make our wedding an～to remember.让我们把婚礼办成永远铭记的盛会。They have the date fixed for the big～.他们已将举行这个盛大集会的日子定了下来。〖同〗event，occurrence，happening;

(4)理由;必(需)要(reason;need;requirement)[U](fml)：You have no～to do that/be angry.你没有理由去做那件事/生气。There was no～for a doctor.没有必要请医生。The debate had to be postponed，by～of the illness of one of the principal speakers.由于主要发言人之一患病，辩论不得不延期举行。〖同〗 reason，cause，need;

(5)起(近)因(immediate but incidental cause of some action or result)[C](fml)：The dog which was the～of the quarrel had run away.引起这场争吵的那条狗跑掉了。The real causes of the strike are not clear，but the～was the dismissal of two workmen.罢工的真正原因不太清楚，但起因是两个工人被解雇。What was the～for all that laughter?这都是笑什么?

on occasion 有时;必要时(fml)：I ride my bicyele on～.我有时骑自行车。

on the occasion of sth值此……之际，在……的时候(fml)：We bought her the picture on the～of her 70th birthday.我们在她70岁生日时给她买了这幅画。

v 引起(be the cause of sth.)(fml)[T+n，D+n+n，D+n+prep(to)]：What～ed his remark? 是什么引起他这番话? The remark～ed a burst of applause.这番话引起一阵掌声。His behaviour～ed (us) a lot of trouble/much anxiety.他的所作所为(给我们)惹了许多麻烦/使我们非常担心。This discovery～ed me no surprise.这一发现并没有使我感到惊奇。The lack of cooperation～ed much grief to them.缺乏合作给他们造成许多痛苦。

→occ′asional adj 不时的，偶然的;应对的;oc′casionally adv不(有)时;偶尔;

【辨异】1)occasion 与opportunity和chance的区别见CHANCE。2)occasion与cause的区别见CAUSE。