I once overheard a remark from a person who had just been in Italy.

overheard 是动词 overhear 的过去式，overhear 由前缀 over-（表示"超过、在...之上"）和动词 hear（听）组成，意思是"无意中听到、偶然听到"，指在别人不知情的情况下听到他们的谈话。