ʕrb / Semitic roots
To enter, stand surety or bail for, guarantee.
1. arbiter, from Latin arbiter, judge, from Phoenician (Punic) *ʕarb, surety, guarantee.
2. earnest2, from Greek arrabōn, from Canaanite *ʕirrabōn, pledge, surety, akin to Hebrew ʕērābôn, from *ʕaraba, to enter, stand surety for.
3. eruv, from post-Biblical Hebrew ʕêrûb, eruv, verbal noun of ʕērēb, to mix, denominative verb from Hebrew ʕēreb, mixture (perhaps < *"an entering among").
4. Arabic root form ġrb, to depart. Maghreb, Morocco, from Arabic maġrib, place where the sun sets, west, from ġaraba, to depart, set (of the sun).