The original sense of the root was:
The most influential branch is probably the one around “pass” which is based on the idea of extending your leg to make a step. But there are other offspring as well.
Here’s an overview over the various English members of that family:
- pass (Originally: “taking a step”, also to take a measure, so there’s a sense of the “expanse” in it)
- passage, passenger, passport
- expand, expansive (The root combined with the “ex”-prefix which here expresses “outward”)
- patent (Originally: “lying open” for an “open letter”)
- fathom (Originally a measure done by stretching out the arms, then shifted toward embracing, grasping)