I ran into 辞書, 辞典 and 字引 in JLPT vocabulary lists, and they are all translated as "dictionary". Are the words completely interchangable, or is there some connotation/context difference between them?

shang Wrote:I ran into 辞書, 辞典 and 字引 in JLPT vocabulary lists, and they are all translated as "dictionary". Are the words completely interchangable, or is there some connotation/context difference between them?

They mean pretty much the same thing. Actually, most of the time 辞書 and 辞典 are interchangeable. The difference is the latter could imply the dictionary is large. But you can refer to a large tome as 辞書, and a lot of native speakers say 辞典 when talking about a relatively small dictionaries.

You might often find 辞典 in names of dictionaries. The only example I can come up with where 辞書 is almost exclusively used is 電子辞書 (electronic dictionary). 電子辞典 makes perfect sense but is used less frequently.

字引 sounds old at least to me, though it is still used fairly often. This word is usually used as a single word, so 国語字引, 電子字引, etc sound unnatural. 生き字引 (walking dictionary) is an exception of this rule, but I think this is kind of an idiom.