Recon

google

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early 19th century: from French, from reconnaître ‘recognize’ (see reconnoitre).

wiktionary

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Contracted form of reconnaissance.

Contracted form of recombination +‎ -on, coined by American molecular biologist Seymour Benzer in 1957 as "[…] the smallest element in the one-dimensional array that is interchangeable (but not divisible) by genetic recombination." [1]

etymonline

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recon

military slang shortening; 1918 for reconnaissance (n.); 1966 for reconnoiter (v.).