Here are two suggestions taken from the site http://www.englishforums.com/English/TraditionVsCustom/nnmqj/post.htm 1. A custom is a behaviour adhered to by a group of people on a regular basis. Example shaking hands when greeting people, serving afternoon tea, or sending cards as a "Thank you". These are things done on a regular basis in an agreed upon manner. A tradition is a behaviour adhered to a group of people on specific occasions that occur regularly. 2. According to Eric Hobsbawm (1983) Custom is what people do and tradition is the formalization of those actions with material things and artifacts. For example in British courts judges pass judgements etc. 'Tradition is the wig, robe and other formal paraphernalia and ritualized practices'. I included the latter because Hogsbawn passed away this week. And from my enormous Russian-English словарь: custom = обычай tradition = традиция