english
1
general::
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]
American Heritage Idioms
2
general::
Phrase(s): in secret secretly. • They planned in secret to blow up the bridge. • I will tell her in secret so no one else will hear.
McGrawhill's American Idioms And Phrasal Verbs