Koichi demanded an explanation about the wet character dictionary from Viet.
It suddenly started pouring rain and the kanji dictionary I was holding got soaking wet.
I bought this calligraphy character dictionary at a secondhand bookstore over there.
Letter rules can be found in a character dictionary. In Japanese, one kanji "letter" or "character" can hold a lot of information, so you have dictionaries dedicated to kanji meanings. That's what this is.
This word is a little old-fashioned these days, so you might also see 漢字辞典 used for a character dictionary. (You'll learn 辞典 soon, if you haven't already!)
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.