Confidant
mid 17th century: alteration of confident (as a noun in the same sense in the early 17th century), probably to represent the pronunciation of French confidente ‘having full trust’.
wiktionary
From French confident.
etymonline
confidant (n.)
1610s, confident, "(male) person trusted with private affairs," from French confident (16c.), from Italian confidente "a trusty friend," literally "confident, trusty," from Latin confidentem (nominative confidens), present participle of confidere "to trust, confide," from assimilated form of com, here perhaps an intensive prefix (see com-), + fidere "to trust" (from PIE root *bheidh- "to trust, confide, persuade"). The spelling with -a- and the pronunciation with the stress on the last syllable came to predominate 18c. and might reflect the French pronunciation.
