a join made by tying together two pieces or ends of string, rope, etc. （用绳索等打的）结 
to tie a knot 打结 Tie the two ropes together with a knot. 将这两根绳子打结系在一起。 Tie a knot in the rope. 在绳子上打个结。 Sailors had to know lots of different knots. 水手们必须知道许多不同的绳结。
Oxford Collocations Dictionaryadjective- loose
- tight
- tangled
- …
- do
- tie
- undo
- …
- knot in
- a knot in your stomach
a way of twisting hair into a small round shape at the back of the head 发髻 a tight mass in something such as hair or wool, where it has become twisted together 结婚；结成夫妻 hair full of knots and tangles 缠结在一起乱糟糟的头发
a hard round spot in a piece of wood where there was once a branch 节子；节疤 a small group of people standing close together 一小群人 Little knots of people had gathered at the entrance. 一小群人聚集在入口处。
a tight, hard feeling in the stomach, throat, etc. caused by nerves, anger, etc. （由紧张、恼怒等引起的胃、喉等的）痉挛，郁结，哽咽，哽塞 a unit for measuring the speed of boats and aircraft; one nautical mile per hour 节（船和航空器的速度计量单位，每小时一海里）
in string/rope绳索
of hair头发
in wood木头
group of people一群人
of muscles肌肉
speed of boat/plane船／飞机的速度
Word OriginOld English cnotta, of West Germanic origin; related to Dutch knot.
Idioms
at a rate of knots
- (British English, informal)
very quickly 飞快地；迅速地 She's getting through her winnings at a rate of knots. 她正以飞快的速度赢回奖金。
More Like This Silent lettersSilent letters
tie somebody/yourself (up) in knots
- (informal)
to become or make somebody very confused （使）大惑不解，糊涂 I got myself tied up in knots when I tried to explain the legal system to them. 当我试图向他们解释法律制度时，我陷入了困境。
tie the knot
- (informal)
to get married 结婚；结成夫妻