无济于事
wú jì yú shì · HSK 7
to no avail
无济于事 = 无 no + 济 help + 于 to + 事 matter: no help to the matter
济 also means to aid or relieve (as in 救济 relief aid). So the four characters spell out no aid reaches the affair — your effort brings no help to the situation, hence to no avail.
无 — top 一 + 林-like middle + fire radical 灬 below
Originally a pictograph of a person dancing while holding ornaments or tassels, meaning 'to dance' — the ancestor of 舞. It was borrowed phonetically to write the negative 'not have / without,' and the dance meaning was reassigned to 舞 with an added foot element. The simplified form 无 comes from an ancient variant.
于 — two horizontal strokes 二 + vertical hook 亅
于 originated as a pictograph of breath or sound flowing outward, depicting exhalation through a passage. In oracle bone script it resembled a curved line showing motion or extension. Over time it became a grammatical preposition meaning 'at,' 'in,' or 'to,' losing its original concrete sense.
事 — hand 又 holding a banner/tablet on a pole
Originally a pictograph of a hand (又) grasping a pole or ceremonial banner used by an official, depicting the act of conducting court business. From this it came to mean 'affair, matter, business, service.' It shares an ancient origin with 史 (scribe) and 吏 (official).