1. Root

 2.dʰer

2. Lexical meanings

 EN: darkness, make muddy

3. Comparative evidence

4. Formally comparable roots

 1.dʰer, 1.dʰreu̯, 1.dʰreu̯gʰ, 1.dʰregʰ, 1.dʰreǵʰ, 2.dʰregʰ, 2.dʰreu̯, 2.dʰreu̯gʰ, 3.dʰer, 3.dʰreu̯, dʰerkh₂, dʰerkʷh₂, dʰerḱh₂, dʰerg, dʰerh₂bʰ, dʰerh₂gʰ, dʰerh₃, dʰers, dʰerǵʰ, dʰreb, dʰrebʰ, dʰragʰ, dʰreh₂gʰ, dʰreǵ, dʰrei̯bʰ, dʰrei̯d, dʰreu̯b, dʰreu̯bʰ, dʰreu̯s, dʰerbʰ

5. Formally/Semantically comparable roots

 dʰerh₂bʰ, dʰerh₂gʰ

6. Revised root variants

7. Comments

8. References

Watkins 2011 = Watkins, Calvert. 2011. The American heritage dictionary of Indo-European roots. 3rd revised ed. Boston, New York: Houghton Mifflin Harcourt.