Meaning of “chain” - Learner’s Dictionary

chain

noun uk us /tʃeɪn/
METAL RINGS [ C, U ]

A2 a line of metal rings connected together:

a bicycle chain
She wore a gold chain around her neck.
The hostages were kept in chains.
BUSINESS [ C ]

B1 a number of similar shops, restaurants, etc owned by the same company:

a chain of hotels/supermarkets
EVENTS [ C ]

B2 a series of things that happen one after the other:

His arrival set off a surprising chain of events.

(Definition of “chain noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)