secret meeting; closed-door session
Refers to a meeting or conference held in private, not open to the public or unauthorized persons. Often used in political, corporate, or diplomatic contexts.
The issue was discussed in a closed-door session.
The contents of the secret meeting must not be leaked outside.
内密 is a na-adjective meaning 'confidential' or 'private', often used for keeping matters secret, whereas 秘密会 is a concrete noun for a secret meeting.
Compound of 秘密 (secret) + 会 (meeting, gathering). The word follows standard Sino-Japanese compounding patterns.