From Longman Dictionary of Contemporary Englishbest friendbest friendBESTthe friend that you know and like better than anyone else She was my best friend in college. → best
Examples from the Corpus
best friend• Although many people would disagree, radio is without doubt the musician's best friend.• He was not allowed to mention the slaughtering to anyone, not even as a special secret between best friends.• I also learned to become my own best friend.• He was like a kid who had found a new best friend, and she was it.• When Julie had a home problem, her two best friends at work tried to offer advice based on their own experiences.• Caroline and her best friend both had babies within three weeks of each other.• We lived next door to each other when we were kids, and we've been best friends ever since.• Stuart is just my brother's best friend - I've known him since I was six.• Trials so that her injured best friend Kay Poe could advance.• Didn't any of his best friends tell him?• After all - the man was one of his best friends, wasn't he? 