What's the difference between i.e. and e.g.?
"flat-bottomed boat" (especially one to support a temporary bridge), 1670s, from French pontoon, from Old French ponton (14c.) "bridge, drawbridge, boat-bridge; flat-bottomed boat," from Latin pontonem (nominative ponto) "flat-bottomed boat," from pons "bridge" (see pons). Pontoon bridge is first recorded 1778.