Secretive

google

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mid 19th century: back-formation from secretiveness, suggested by French secrétivité, from secret ‘secret’.

wiktionary

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From Middle English secretife, equivalent to secret +‎ -ive.

secretive (not comparable)

etymonline

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secretive (adj.)

"inclined to secrecy," 1815 (implied in secretiveness); see secret (n.) + -ive. The word also was in Middle English with a sense "secret, hidden" (mid-15c.). Related: Secretively.