bell,

• bell [countable]
• 1 a piece of electrical equipment that makes a ringing sound, used as a signal or to get someone's attention
• ring/press the bell
• He rang the bell and waited for someone to answer the door.
• She walked up the path and rang the door bell.
• a bell rings/goes
• The bell went and everyone rushed out of the classroom.
• 2 a hollow metal object like a cup with a piece of metal hanging inside it, which makes a ringing noise when it moves or you shake it:
• church bells
• 3

  give somebody a bell

   British Englishspoken to telephone someone:
• I must give Vicky a bell later.
• 4 something that is shaped like a bell:
• the bell of a flower

• ➔ alarm bells ring 

  at alarm1 (5)

  ; ➔ as clear as a bell

  atclear1 (10), diving bell

  ; ➔ ring a bell

  at ring2 (4)

• semi-automatic also sem‧i‧au‧to‧mat‧icAmerican English
• a semi-automatic weapon moves each bullet into position ready for you to fire, so that you can fire the next shot very quickly
• —semi-automatic noun [countable]

• cor‧al [uncountable]
• a hard red, white, or pink substance formed from the bones of very small sea creatures, which is often used to make jewellery

• scan‧ner [countable]
• 1 a machine that passes an electrical beam over something in order to produce a picture of what is inside it [↪ scan]:
• a high-tech body scanner
• 2 a piece of computer equipment that allows written or printed information to be taken onto a computer and stored there [↪ scan]

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.