“活字典”常见的英文表达是 “a walking dictionary” ，该短语形象地描绘出某人像会行走的字典一样，知识丰富、对词汇等信息了如指掌。
例句：
Our English teacher is a walking dictionary. Whenever we have doubts about a word, he can always give us a detailed explanation.（我们的英语老师是个活字典。每当我们对某个单词有疑问时，他总能给出详细的解释。）
He is regarded as a walking dictionary in the field of ancient Chinese literature.（他在中国古代文学领域被视为活字典。）