He bypassed the traffic jam on the highway by taking a side road.

bypassed 是动词 bypass 的过去式。bypass 由前缀 by-（表示"旁边、绕过"）和 pass（"通过"）组成，字面意思是"从旁边通过"，引申为"绕开、避开"的意思。在句中指"避开交通拥堵"的行为。