double-O

[ duhb-uh l-oh ]
/ ˌdʌb əlˈoʊ /

noun, plural dou·ble-Os. Older Slang.

careful scrutiny or close inspection.

Origin of double-O

1915–20; after the two o's in once-over
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019