in secret
Away from others; in private. We need to meet in secret so that the paparazzi don't see us together. You better speak to him in secret about that, instead of ambushing him in front of the whole staff.
in secret
secretly. They planned in secret to blow up the bridge. I will tell her in secret so no one else will hear.
in secret
Unknown to others, privately. For example, They met in secret, or, as Shakespeare put it in Love's Labour's Lost (5:2): "One word in secret." [Second half of 1400s]
in secret
Without others knowing.