Trigger words are terms with well-defined meanings which have been endowed with additional power, often emotional in nature, by use and repetition in the legacy media and government schools, employed to evoke a visceral response and short-cut rational thought in the reader.
Consider, for example, “controversial”. By itself, the word is entirely devoid of political tilt in any direction: it simply denotes something about which people disagree with some degree of ferocity. But look at how it’s used: legacy media outlets consistently label issues they oppose as “controversial”, while those they endorse, equally disputed amongst the public, appear without an adjective.
The bias is never explicit, but deliciously subtle and effective: the “controversial” issue is, inarguably, controversial, while the unlabeled one appears, by contrast, to be the consensus view of all right-thinking people.