multi-moding refers to commuting. Basically, it means that you're changing the vehicle somewhat frequently. For example, if you bike to a train or subway then take the train to the city, then bike the rest of the way to work... that's a multi-modal commute. You've changed the vehicle from bike to train to bike.

There are a gazillion varieties... here's my work commute as an example...

Bike to the L
Take the L downtown
Bike to the Metra
Take the Metra to Lombard
Bike to the Office

--sam