The combination is a powerful metaphor: the lips launch pointed, spear-like attacks (枪), while the tongue deftly wields words like a sword (剑) to counter and strike. Together, they create the image of a full-blown verbal battlefield.
In Chinese culture, where maintaining harmony (和) and preserving “face” (面子) are often paramount, direct confrontation is typically avoided. The idiom 唇枪舌剑 is therefore particularly striking because it describes a situation where these social norms have been set aside for an all-out verbal conflict. It's a testament to the power of language as both a tool of intellectual prowess and a weapon of conflict. Compared to the Western concept of a “spirited debate,” 唇枪舌剑 often carries a more adversarial and less friendly connotation. A “spirited debate” might imply a passionate but ultimately constructive exchange of ideas among colleagues. 唇枪舌剑, however, strongly implies a zero-sum game—a battle to be won, where one side's victory is another's defeat. It highlights the combative aspect of the argument over the collaborative one. It is often used to describe situations where reputations, deals, or legal outcomes are on the line.
This Chengyu is literary and somewhat formal, but it's widely understood and used in various modern contexts to add descriptive flair.