1.custom的基本意思是“风俗,习惯,惯例”,指一个团体或社会长期以来形成的传统,也可指个人的习惯,有单复数形式,用于泛指时多用单数; 表示某种习俗时可加不定冠词a,指各种风俗习惯时也可用复数。
2.custom还可作“光顾”“顾客”解。作“光顾”解时指去某商店购物的行为; 作“顾客”解时,指“顾客群”而不指具体某人,不可数,无复数形式。
3.custom作“海关,关税”解时,是复数名词,用作主语修饰另一个名词时仍需使用其复数形式。

Social customs are greatly different from country to country.各个国家的社会风俗很不相同。
Custom has a great influence on his behaviour.习俗对他的行为举止影响很大。
The celebration of Christmas is a custom.庆祝圣诞节是一种习俗。
You must conform yourself to the custom of the land.你必须遵从这个国家的习俗。
The work glances at the customs of ancient cultures.该著作述及古代文化的习俗。
I think these interesting old customs should be preserved.我认为这些有趣的旧习俗应该保留下来。
It was Tom's custom to get up early and go for a walk before breakfast.汤姆习惯早起床,并在早餐前散步。
Eating hot dogs is an American custom.吃热狗是美国人的一种习惯。
It is my custom to go to France for my holiday.我习惯于到法国度假。
It is the custom of foreigners to do so.这样做法是外国人的习惯。
The custom has now become a rule.那种习惯现已变为常规。
Low prices draw custom.低价格吸引顾客。
We've lost a lot of custom since our prices went up.自从提价以后,我们失去了许多顾客。
It took us only four minutes to get through the Customs.我们用4分钟的时间通过了海关。
She is seeing her baggage through customs at the airport.她正在机场办理行李过关的手续。
We had to pay customs on the camera equipment we bought abroad.我们在国外买的摄影器材要付关税。
I followed her into the Customs Building.我跟着她进了海关大楼。
The Customs formalities are simple.海关检查手续很简单。
The Customs have found heroin hidden in freight.海关查出了隐藏在货物中的海洛因。

custom, convention, tradition
参见tradition条。
custom, habit
这两个词都有“习惯,习俗,风俗”的意思。其区别是:
1.custom指群体经过一段时期不断沿用而变成的习惯或惯例; habit指某个人反复地做某种动作,久而久之形成的自然习惯或习性,行动时不用思索。例如:
This custom is on the decline.这种风俗渐渐消失。
He has the irritating habit of smoking during meals.他有边吃饭边抽烟那让人讨厌的习惯。
2.custom有时也指个人习惯,这时与habit的区别是:habit常指不好的习惯,而custom则常指良好的习惯。例如:
It is his custom to take a cold bath every morning.他每天早晨有洗冷水澡的习惯。
He has a habit of biting his lips when he is puzzled.他感到困惑时有咬嘴唇的习惯。

脱鞋进屋是日本人的习惯。
［误］  It is a custom to the Japanese to remove their footwear before entering a house.
［正］  It is a custom among the Japanese to remove their footwear before entering a house.
［析］  custom作“风俗”,“习惯”解,是指社会、民族的风俗习惯,属群体性质的习惯,如表示“是某些人的习俗”时,须在custom之后接介词among。

［同义词］   convention, habit, practice
［词源］ ＜古法语costume(习性,惯用)