secret + -ive

source: [秘密です｜無料GIF画像検索 GIFMAGAZINE 3971018]

(of a person or an organization) inclined to conceal feelings and intentions or not to disclose information:

〈人が〉 «…について» 秘密にしたがる, 隠し立てする «about» ; 無口の

e.g. she was very secretive about her past.

(of a state or activity) characterized by the concealment of intentions and information:

e.g. secretive deals.

(of a person's expression or manner) having an enigmatic or conspiratorial quality:

e.g. a secretive smile.

secretively |ˈsēkridivlē| adverb

secretiveness |ˈsēkridivnəs| noun

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