This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. One who corroborates, or verifies something; one who lends credence by upholding another's story.

"Bill Cosby and his corroborator, Dr Alvin Poussaint recently wrote, Come on People, a book in which they emphasize and tie personal responsibility to the community's progress."