Afoot (adverb)

1. In progress.
2. Being planned or prepared.
3. On foot.

Origin:

Middle english, from a- + foot foot.

Examples:

1. There is a big project afoot to build a new bridge.
2. There is something afoot and I don't know what it is.
3. There's a big plan afoot to revitalize the downtown area.
4. We heard that something was afoot and we wanted to know more.
5. He went afoot to explore the nature trail.