We found 11 dictionaries that define the word thick as thieves:

General (7 matching dictionaries)

1. thick as thieves: Merriam-Webster
2. thick as thieves: Oxford Learner's Dictionaries
3. thick as thieves: Wiktionary
4. Thick as Thieves (Cavo album), Thick as Thieves (TV series), Thick as Thieves (The Temper Trap album), Thick as Thieves (Trooper album), Thick as Thieves (Turner novel), Thick as thieves: Wikipedia, the Free Encyclopedia
5. Thick as Thieves: TheFreeDictionary.com

Business (1 matching dictionary)

6. Thick as Thieves: Legal dictionary

Medicine (1 matching dictionary)

7. Thick as Thieves: Medical dictionary

Miscellaneous (1 matching dictionary)

8. thick as thieves: Idioms

Slang (1 matching dictionary)

9. thick as thieves: Urban Dictionary

Definitions from Wiktionary (thick as thieves) ▸ adjective:  (idiomatic, simile, of friends or members of a group) Intimate, close-knit, tight. Similar: thick, tight, intimate, thickset, thicksome, thick as a brick, thick as a plank, thicketed, thick as two short planks, thickety, more... Opposite: estranged, alienated, hostile Phrases: as thick as thieves, more... ▸ Words similar to thick as thieves ▸ Usage examples for thick as thieves ▸ Idioms related to thick as thieves ▸ Wikipedia articles (New!) ▸ Popular nouns described by thick as thieves ▸ Words that often appear near thick as thieves ▸ Rhymes of thick as thieves ▸ Invented words related to thick as thieves