What is the base word for to go on a journey?

There isn't a single base word for "to go on a journey". The closest we can get is "journey" itself, which is a noun, not a verb.

Here are some ways to express the concept of "to go on a journey" using verbs:

* Travel

* Voyage (for a long journey by sea or in space)

* Wander (to travel without a specific destination)

* Trek (a long and difficult journey)

* Expedition (a journey undertaken for a specific purpose, often exploration or research)

* Sojourn (a temporary stay in a place)

The best word will depend on the specific context and the type of journey you're describing.