In the long-running and often combustible feud between former President Donald J. Trump and the late-night host Jimmy Kimmel, the insults have become almost ritualized. But when Mr. Trump recently referred to Mr. Kimmel as “President Dementia,” the exchange once again illustrated how political grievance and televised comedy now feed off one another in a media ecosystem that rewards spectacle.

The remark came as Mr. Trump criticized entertainment figures at a public event, revisiting a familiar target. “I’ve watched some of the people that host — Jimmy Kimmel was horrible,” he said, before adding that if he could not “beat out Jimmy Kimmel in terms of talent,” he should not be president. Soon after, on his social media platform, he escalated the attack, branding the ABC host “President Dementia,” a pointed personal insult intended to question Mr. Kimmel’s mental acuity.

For Mr. Trump, such language is neither new nor accidental. Throughout his political career, he has relied on derisive nicknames to frame opponents — “Crooked Hillary,” “Sleepy Joe” — as diminished figures unworthy of office or attention. In targeting Mr. Kimmel, the host of “Jimmy Kimmel Live!,” Mr. Trump appeared to deploy a similar tactic, casting a television comedian as both adversary and foil.

The rivalry between the two men stretches back years. Mr. Kimmel, whose monologues often blend celebrity humor with pointed political commentary, has frequently mocked Mr. Trump’s rhetoric, legal troubles and public statements. Mr. Trump, in turn, has responded on social media and at rallies, portraying Mr. Kimmel as emblematic of what he calls a hostile entertainment establishment.

This latest episode followed a familiar script. Mr. Trump delivered a public slight; the insult ricocheted across social media; anticipation built for Mr. Kimmel’s reply. By the time the host walked onto his stage in Hollywood that evening, his audience knew what was coming.

Mr. Kimmel did not ignore the comment. But rather than respond with indignation, he leaned into satire. He opened by mock-praising Mr. Trump’s “talents,” joking that the former president could sing, act and dance — before adding that the only way to contain so much talent might be to “lock him up,” a barbed reference to Mr. Trump’s legal challenges. The studio audience roared.

Addressing the “President Dementia” remark directly, Mr. Kimmel pointed to what he framed as the irony of Mr. Trump questioning anyone’s mental clarity. He played clips of the former president’s own verbal stumbles and digressions, some drawn from rallies and interviews that have circulated widely online. Then came the punchline: being called “President Dementia,” Mr. Kimmel quipped, was “an upgrade — at least it includes the word president.”

Within hours, video of the segment spread across digital platforms. Supporters of Mr. Kimmel hailed the response as deft and unflappable. Mr. Trump’s allies dismissed it as predictable hostility from a partisan entertainer. Cable news programs replayed excerpts; online commentators parsed tone and timing.

Beyond the immediate exchange, the episode underscored how late-night television has evolved into a hybrid of comedy, commentary and cultural battleground. Hosts like Mr. Kimmel, along with peers such as Stephen Colbert and Seth Meyers, have built large audiences by blending humor with explicit political critique. In doing so, they have become targets not only of online backlash but of direct political counterattack.

For Mr. Trump, whose political persona has long been intertwined with media performance, sparring with entertainers offers both risk and reward. Confrontations with television figures can reinforce his image as a fighter against elite institutions. At the same time, they provide comedians with ready-made material, often amplifying the very mockery he seeks to blunt.

Communication scholars note that this dynamic reflects a broader shift in American political culture, in which boundaries between governance, entertainment and personal branding have blurred. Insults become content; rebuttals become viral clips; outrage fuels engagement on both sides.

What distinguishes the Kimmel exchange, observers say, is the contrast in tone. Mr. Trump’s language was blunt and accusatory, aimed at diminishing his critic’s credibility. Mr. Kimmel’s response, by contrast, was structured around irony and inversion — taking the insult and reframing it as absurd. In the economy of late-night television, composure and timing can be more potent than direct confrontation.

Still, neither man is likely to retreat. Mr. Trump continues to campaign vigorously, often framing himself as embattled by cultural and media elites. Mr. Kimmel, whose show reaches millions of viewers nightly, shows little inclination to soften his political barbs.

If anything, the exchange suggests that the feedback loop between politics and entertainment is now self-sustaining. A rally remark becomes a monologue. A monologue becomes a headline. A headline becomes another rally line.

In that cycle, “President Dementia” may be less a singular insult than another chapter in an ongoing performance — one in which humor and hostility share the same stage, and where the applause meter can be as influential as the ballot box.