All 4 Uses

discreet
in
Wide Sargasso Sea
(Edited)

I turned to take her in my arms, I meant to undo the careful plaits, but as I did so there was a soft discreet knock.
Part 2

discreet = trustworthy with secrets and/or inconspicuous or unobtrusive
I happen to know now that she has not returned to Martinique, so I have written very discreetly to Hill, the white inspector of police in your town.
Part 2

discreetly = in a manner that is unlikely to attract attention or cause embarrassment
I read the end of Fraser's letter aloud: 'I have written very discreetly to Hill, the white inspector of police in your town.
Part 2
I also told them to engage a staff of servants whom I was prepared to pay very liberally — so long as they keep their mouths shut, I thought — provided that they are discreet, I wrote.
Part 2 *

discreet = trustworthy with secrets

Definitions:

(1) (discreet as in: discreet--not showy or gossipy)
trustworthy with secrets or subtle (not attracting attention)

This sense of discreet sometimes indicates that something is small (so as not to attract attention) as in "discreet earrings."
(2) (discreet as in: discreet--not foolish)
sensible and careful; possibly having good manners

This sense of discreet is more commonly seen in classic literature than in modern writing. There is may also refer to having the judgment to exercise good manners.
(3) (meaning too rare to warrant focus)