We found 11 dictionaries that define the word punctuation marks:

General (7 matching dictionaries)

1. punctuation marks: Merriam-Webster
2. punctuation marks: Collins English Dictionary
3. punctuation marks: Vocabulary.com
4. punctuation marks: Cambridge Advanced Learner's Dictionary
5. punctuation marks: Wiktionary
6. Punctuation marks: Wikipedia, the Free Encyclopedia
7. Punctuation marks: TheFreeDictionary.com

Art (1 matching dictionary)

8. English-Chinese Dictionary of Graphic Communications (Big 5) (No longer online)

Business (1 matching dictionary)

9. Punctuation marks: Legal dictionary

Computing (1 matching dictionary)

10. Punctuation marks: Encyclopedia

Slang (1 matching dictionary)

11. Punctuation Marks: Urban Dictionary

(Note: See punctuation_mark as well.)

Definitions from Wiktionary (punctuation mark) ▸ noun:  Any of various symbols used in writing and printing to indicate pauses, divisions, etc. and to aid the reader in understanding what is written. ▸ Also see punctuation_mark Opposite: unpunctuated, unmarked, plain, undecorated, unadorned ▸ Words similar to punctuation marks ▸ Usage examples for punctuation marks ▸ Idioms related to punctuation marks ▸ Wikipedia articles (New!) ▸ Words that often appear near punctuation marks ▸ Rhymes of punctuation marks ▸ Invented words related to punctuation marks