• chain
• 
• 1

  joined rings

   [uncountable and countable] a series of metal rings which are joined together in a line and used for fastening things, supporting weights, decoration etc [↪ link]:
• She had a gold chain around her neck.
• a length of heavy chain
• the Mayor's chain of office (=a decoration worn by some British officials at ceremonies)
• pull the chain (=flush the toilet) British English
• a bicycle chain (=that makes the wheels turn)
• 2

  connected events

   [countable] a connected series of events or actions, especially which lead to a final result:
• the chain of events that led to World War I
• The salesmen are just one link in the chain (=part of a process) of distribution.
• a rather complicated chain of reasoning
• ➔ chain of command, food chain
• 3

  shops/hotels

   [countable] a number of shops, hotels, cinemas etc owned or managed by the same company or person
• chain of
• a chain of restaurants
• hotel/restaurant/retail etc chain
• several major UK supermarket chains
• ➔ chain store
• 4

  connected line

   [countable] people or things which are connected or next to each other forming a line
• mountain/island chain
• the Andean mountain chain
• chain of atoms/molecules etc technical:
• a chain of amino acids
• They formed a human chain (=a line of people who pass things from one person to the next) to move the equipment.daisy chains (=flowers tied together)
• 5

  prisoners

   [countable usually plural] metal chains fastened to the legs and arms of a prisoner, to prevent them from escaping
• in chains
• He was led away in chains.
• ball and chain (=a chain attached to someone's ankle at one end with a heavy metal ball at the other)
• 6

  buying a house

   [countable usually singular] British English a number of people buying houses, where each person must complete the sale of their own house before they can buy the next person's house

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