dreh₂-
“to run, to move quickly”Run, trot, travel
A PIE verbal root meaning "to run, to step," continued in Greek drómos (δρόμος, "a running, a racecourse"), whence hippodrome, dromedary, syndrome, and palindrome; and in Germanic *tradą, whence English tread and trade (originally "a path, a course of dealing").
Discussion
The root *dreh₂- ("to run") is reconstructed from Greek dramein (δραμεῖν, aorist "to run"), drómos (δρόμος, "a running, a course"), Old English tredan ("to tread, to step"), and possibly Sanskrit drā́ti ("runs"). Pokorny (IEW 204–205) and Rix (LIV² s.v. *dreh₂-) provide the reconstruction.
Greek drómos (δρόμος, "a running, a racecourse, a road") was extraordinarily productive in compounds: hippódromos ("horse-course," whence hippodrome), prodromos ("running before, precursor," whence prodrome in medicine), palíndromos ("running back," whence palindrome), and syndromḗ ("a running together," whence syndrome). The dromedary (dromás kamḗlos, "running camel") was distinguished from the two-humped Bactrian camel by its speed.
Old English tredan ("to tread, to step, to walk") gave modern English tread. The noun trade (Middle English, "a track, a path, a course of action") originally meant a habitual path or route and only later specialized to mean commercial exchange. This semantic shift from "path/track" to "commerce" is paralleled in other languages.
Notes
gsc-gap: source of "tread", "trade", "dromedary", "hippodrome", "syndrome", "palindrome"
Laryngeal Analysis
Contains *h₂; colours and lengthens preceding vowel.
Ablaut
Full grade *dreh₂-, zero grade *drh₂-.