knives, knifes, knifing, knifed
(knives is the plural form of the noun and knifes is the third person singular of the present tense of the verb.)
1) N-COUNT A knife is a tool for cutting or a weapon and consists of a flat piece of metal with a sharp edge on the end of a handle.

...a knife and fork...

Two robbers broke into her home, held a knife to her throat and stole her savings.

2) VERB To knife someone means to attack and injure them with a knife.

[V n prep] Dawson takes revenge on the man by knifing him to death...

[V n prep] She was knifed in the back six times. [Also V n]

3) N-COUNT A surgeon's knife is a piece of equipment used to cut flesh and organs during operations. It is made of metal and has a very thin sharp edge.
PHRASE: PHR after v If you go under the knife, you have an operation in a hospital.

Kelly was about to go under the knife when her surgeon stopped everything.

5) PHRASE: knife inflects, PHR after v If someone does something like a knife through butter or like a hot knife through butter, they do it very easily.

Spending by Japanese companies has left them more competitive than companies in other nations. They will be cutting through the competition like a hot knife through butter.

6) PHRASE If you have been in a place where there was a very tense atmosphere, you can say that you could have cut the atmosphere with a knife. [mainly BRIT]

Officials hung the flag upside down. You could have cut the atmosphere with a knife.

7) PHRASE: V inflects, usu PHR for n If a lot of people want something unpleasant to happen to someone, for example if they want them to lose their job, you can say that the knives are out for that person. [mainly BRIT]

The Party knives are out for the leader.

8) PHRASE: V inflects If you twist the knife or if you turn the knife in someone's wound, you do or say something to make an unpleasant situation they are in even more unpleasant.

Hearing his own plans was like having a knife turned in his wound...

It is the turn of Latvia to twist the knife.

English dictionary. 2008.