friendship between old and young people; (become) the best of friends in spite of the difference of age
Example Sentences:
1.
Your father and i have been friends since time began 我和你父亲是忘年之交了
2.
He is touched by the boys compassion and the two become friends regardless of their age difference . as a token of thanks , the old man teaches the boy to play the lute 温暖的情谊使老人感到欣慰，两人结为忘年之交；老人将琴艺传授给他，作为回报与寄托。
