na-adjective
Describes speech, writing, or behavior that follows a set pattern without genuine feeling or spontaneity. Often carries a slightly negative nuance of being mechanical or lacking warmth.
彼の挨拶はいつも公式的で、心がこもっていない。
His greetings are always formulaic and lack sincerity.
na-adjective
Used when something is done in an official capacity or according to formal procedures, without the negative connotation of being mechanical. Less common than 公式 (こうしき) alone.
公式的な発表は明日行われます。
The official announcement will be made tomorrow.
Compound of 公式 (こうしき, 'official; formula') + 的 (てき, '-like, -ish'). The combination yields 'formulaic' or 'official-like'.