soiling

To make dirty.

To become dirty or soiled.

“Light colours soil sooner than dark ones.”

To stain or mar, as with infamy or disgrace; to tarnish; to sully.

To dirty one's clothing by accidentally defecating while clothed.

To make invalid, to ruin.

To enrich with soil or muck; to manure.

To feed, as cattle or horses, in the barn or an enclosure, with fresh grass or green food cut for them, instead of sending them out to pasture; hence (such food having the effect of purging them), to purge by feeding on green food.

“to soil a horse”

An act of making dirty.