fine-tooth comb

US: (fīn′to̅o̅th′)

WordReference Random House Unabridged Dictionary of American English © 2026

fine′-tooth comb′  (fīn′to̅o̅th′), 

1. Clothing a comb having narrow, closely set teeth.
2. go over or through with a fine-tooth comb, to examine in close detail; search thoroughly;
   fine-comb:
   The police went over the apartment with a fine-tooth comb.

Also, fine′-toothed comb′  (fīn′to̅o̅tht′, -to̅o̅ᵺd′). 

• 1830–40

Collins Concise English Dictionary © HarperCollins Publishers::

fine-tooth comb, fine-toothed comb noun

1. a comb with fine teeth set closely together
2. go over with a fine-tooth comb, go over with a fine-toothed comb, go through with a fine-tooth comb, go through with a fine-toothed comb ⇒ to examine very thoroughly