Synonyms of 'inseparable'
The two girls were inseparable.
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A bosom friend is a friend who you know very well and like very much indeed.
They were bosom friends.
You say that people are close to each other when they like each other very much and know each other very well.
She and Linda became very close.
Thesaurus for inseparable from the Collins English Thesaurus
If one thing is inseparable from another, the things are so closely connected that they cannot be considered separately.