Noun

(uncountable) The act of connecting.

The point at which two or more things are connected.

the connection between overeating and obesity

My headache has no connection with me going out last night.

* {{quote-news

, year=2004 , date=April 15 , author= , title=Morning swoop in hunt for Jodi's killer , work=The Scotsman citation , page= , passage=A spokesman for Lothian and Borders Police said: "We can confirm that a 15-year-old boy has been arrested and charged in connection with the murder of Jodi Jones. A 45-year-old has also been arrested in connection with allegations of attempting to pervert the course of justice. A report on this has been sent to the procurator fiscal." }}

A feeling of understanding and ease of communication between two or more people.

As we were the only people in the room to laugh at the joke, I felt a connection between us.

An established communications or transportation link.

computers linked by a network connection

I was talking to him, but there was lightning and we lost the connection .

(transport) A transfer from one transportation vehicle to another in scheduled transportation service

The bus was late so he missed his connection at Penn Station and had to wait six hours for the next train.

A kinship relationship between people.

Noun

(uncountable) Susceptibility to attack or injury; the state or condition of being weak or poorly defended.

The country recognized their defence vulnerability after an airplane landed in front of the central square without any consequences.

(countable) a specific weakness in the protections or defences surrounding someone or something.

(computing) a weakness which allows an attacker to reduce a system's security