IPA: /ˈkɑːrˌpuːlər/
KK: /ˈkɑrˌpulər/
A person who shares a car ride with others to travel to the same destination, usually to save money or reduce traffic.
As a carpooler, she enjoys both saving on gas and making new friends during her commute.
Carpooler is formed from "car" (from Latin "carrus", meaning a wheeled vehicle) and "pool" (from Middle English "pol", meaning a shared resource or group). The suffix "-er" indicates a person who engages in the action. Thus, a carpooler is a person who shares a car with others as a resource for transportation.
Think of a 'car' as a wheeled vehicle and 'pool' as sharing a resource. A carpooler is someone who shares a car with others.