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

• Lexulous
• Wordscraper
• Wordosaur

adj. superlative form of crumbly: most crumbly.

"She selected from the brown jar on the table three of the brownest, crumbliest, most perfect cookies, with a walnut meat perched atop of each, placed them temptingly on the saucer and, descending the steps, came swiftly across the grass to the triumphant"