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practice; experience; habituation
being used to; being comfortable with; being experienced in
長年の馴れから二人は空気のような存在になった。
Through years of familiarity, the two became as natural as the air to each other.
馴れが生じると仕事に対する緊張感が薄れる。
When complacency sets in, the sense of tension toward work fades.
環境への馴れが早い人は適応力が高い。
People who get accustomed to new environments quickly have strong adaptability.