THESSALONIKI, Greece — To understand how deeply the name Macedonia is embedded in the Greek psyche, look no further than Greece’s second city, Thessaloniki. It’s the capital of the northern region of Macedonia, the historical center of a long-running feud with the neighboring country of Macedonia, whose claim to the name is the focus of United Nations-mediated negotiations.

In Thessaloniki, there is a Greek Ministry for Macedonia. The international airport carries the name Macedonia. The city has a university and research institute with the same name. And the Museum of the Macedonian Struggle in Thessaloniki holds in its curated halls the troubled history of the region.

The dispute is so contentious that when Thessaloniki’s liberal mayor, Yiannis Boutaris, used the name Macedonia in a visit to Skopje, the capital of Macedonia, in November, he was promptly branded a traitor on social media. He also came under fire for suggesting that Thessaloniki’s airport could drop the name Macedonia and for speaking of “three Macedonias” — one in Greece, one in Bulgaria and one in the neighboring Balkan country.

(There’s no evidence that the Macedonia dispute prompted the brutal beating that the 75-year-old mayor, known for his liberalism and outspoken views, endured from a far-right mob during a ceremony last month to commemorate the World War I genocide of Pontic Greeks by Turkish forces.)