"Human Shields", like its elder brother "ethnic cleansing", is part of the lexicon of modern Balkan wars, brought about by the peculiar situation in which rival ethnic groups fight each other, yet continue to have their civilians mixed together.
NATO reported earlier this week that Serbia was using large numbers of ethnic Albanian refugees as human shields, bunching them around tank convoys, hoping thus to deter prowling jets. The practice came in with the air strikes: two days after the first NATO bombing, Serbs rounded up refugees from around the village of Chirez.
Bunching them in the middle of a tank convoy, they forced them to march with the vehicles along a few miles of exposed road under a clear blue sky to the outskirts of Srbica, scene of recent heavy fighting. The refugees were released unharmed, having served their purpose. If there were any NATO jets overhead at the time, they would presumably have seen the great swarm.
This week photographs released by NATO of the village of Glojane show several hundred refugees in a field, their cars around them. And sitting in a loose semi-circle close by are six Serbian tanks. Refugees arriving in Albania say Serb tanks have been backed into houses, or covered in hay, to persuade NATO not to bomb.
This practice was well known in Bosnia's war. Bosnian Croats used a handful of Muslims for this purpose when making a tactical move outside the town of Vitez in 1993. Many "human shields" in that war saw service laying mines, their own soldiers in opposing trenches unable to open fire.
And on a larger scale, Bosnia's mostly-Muslim government used them, if not as shields, then as chess pieces at Srebrenica in 1993. Three years before Serb forces massacred the male population of this town, they had a chance to evacuate. They were turned back, not by Serbs, but by Muslim forces near the town of Tusla: under the realpolitik of the time, the Sarajevo government decided that soldiers would fight better to defend the enclave, and aid agencies would fight harder to get in, if the civilian population remained trapped in there.
Now, western officials said, the need for such "shields" was the reason why Serbia abruptly halted its "ethnic cleansing" of Kosovo last week. The "missing" refugees are in fact thought to be held as mobile shields - to be deployed as necessary. These people, assuming they have enough food to keep alive, could be used to protect tank convoys, or, more ambitiously, could perhaps be sent back to villages that Serbia does not want to bomb.
The simple fact of an estimated 800,000 ethnic Albanians continuing to live in Kosovo has given NATO pause for thought. Commanders had expected that the Serb "cleansing" would give them an empty "free fire" zone.
Wednesday's air attack proves that, tragically, not to be the case.
Human shields also bring NATO face-to-face with the problem of limited war, another problem that is relatively new. In previous centuries armies would give it their all. Now NATO is humbled not by Serb firepower but by a list of constraints which say it must not itself lose casualties, must take care about "collateral" damage, and must even avoid killing too many of its enemy, or destroying its economy too comprehensively, lest that enrage world opinion.
Perhaps this disaster will also mark the realisation among the public of the NATO nations that, despite all the technology, we have yet to arrive at a "clean" war. In the Gulf War, Britain lost most of its dead in a single incident - the mistaken US rocket attack against a British troop carrier.
In the Falklands, bureaucratic oversights led to guardsmen being left too long on two troop ships, at Bluff Cove, which were then bombed by the Argentine air force.
Recent bombing of Iraq led to the deaths of civilians when a laser-guided bomb somehow skipped its laser beam and "took out" a street.
Murkiness is the first law of war - it may be impossible to know if the dead were human shields, or just happened to be corralled there. But the second is that war hurts, an obvious truth that seems to escape the NATO public, at least for the opening weeks of recent wars.
Partly this is the fault of the politicians, who in their urge to make everything - school closures, tax rises - seem all right, try to present the coming battles as no more horrible than an arcade game, with technology ensuring that only the bad guys get killed - and no more of them than is necessary.
The Geneva Conventions, signed in 1949 in the world's attempt, in this atomic age, to try and make war less ghastly, prohibits civilians, or military prisoners, being put in unnecessary danger.
But these conventions also prohibit rapes, mass murder and the "cleansing" of entire populations. They also have something to say about indiscriminate bombing, something NATO may have to bear in mind if any more trains, private houses or other "collateral" targets get hit.
But perhaps the practice of human shields has met its match. If this column were indeed being used for this purpose, then the idea didn't work. And Serb commanders may now be more circumspect about moving their armour, with or without unarmed refugees massed around them.