At a White House event yesterday honoring Navajo code talkers, President Trump called Senator Elizabeth Warren “Pocahontas,” as he has on many past occasions. Native American leaders, among so many others, are rightly decrying the disparaging remarks as a racial slur, as it drags native peoples into the mud—and literally so, if we look to the etymology of slur.

Slippery, sloppy slur
A slur, or “insulting or damaging remark,” is first attested in 1609, according to the Oxford English Dictionary (OED). Since then, the term has especially narrowed to the disparagement of a particular group of people, as we see in Trump’s comments.
But in the early 1400s, slur, or sloor in Middle English, was “mud”—a thin, loose, washy mud. As the great philologist Walter Skeat explains, “The [original] sense is ‘to trail,’ or draggle; hence, to pass over in a sliding or slight way, also, to trail in dirt, to contaminate.”
Slur naturally extended as a verb for “smear” or “stain” by the 1600s, from where it made its metaphorical jump to disparagement. It was used of smoothly singing or playing music by the 1740s, as one slurs notes on a saxophone, and of blurred, indistinct speech by the 1890s, as drunks slur their speech.
For the origin of slur, etymologists point to similar terms in Dutch, like sleuren or slooren, “to trail in mud.” They also connect slur to the East Frisian sluren, “to go about carelessly,” and Norwegian slora, “to be careless.”
Skeat, for his part, grounds slur in the same root as slide: the Germanic *slid-, also source of sled, sleigh, and sledge. The OED is more reserved, suggesting a possible connection to the Dutch slore, a “sluttish woman.” (The word slut, it’s worth noting, originally demeaned women seen as dirty or untidy.)
While its ultimate origins may be muddy, the sl- in slur no doubt shows some slippery sound symbolism, or phonesthesia: slop, sludge, slush, slime, slag, sloven, among others—all of which more aptly sound like the character of someone who issues slurs.