帖子
tiě zi · HSK 7
post
💬📨 帖 = written note/card + 子 noun-suffix; a posted message or invitation
帖 (tiě) is a written card, note, or invitation; 子 (zi) is a neutral-tone noun ending. Together 帖子 is a slip of writing sent or pinned up — nowadays most often a forum post or online message.
子 — pictograph of a baby/child with arms out
子 began as a pictograph of a swaddled infant with a large head and outstretched arms, originally meaning 'baby' or 'child.' From there it broadened to 'son,' 'offspring,' and a respectful suffix for masters like 孔子 (Confucius). It also became one of the twelve earthly branches.