聯

Compound character (semantic–semantic):

耳 (귀 이, “ear”) — represents hearing, side-by-side placement.

關 (관, “to close, relation”) — represents interconnection, linkage.

Together, they convey the sense of “joining, linking parts together like ears at a gate,” extending to the abstract meaning “to connect, unite.”

Closely synonymous with 連 (잇다, to connect), which later became the simpler, more common form.

聯盟 (연맹) — alliance, coalition

聯絡 (연락) — contact, communication

聯合 (연합) — union, association

對聯 (대련) — poetic couplet (often pasted on doors)

聯隊 (연대) — regiment, corps

In traditional culture, 對聯 (duìlián) refers to the paired poetic couplets often displayed at doorways, especially during New Year.