Adjectives

(s)afoottraveling by foot“she was afoot when I saw her this morning”
(s)afoot, underwaycurrently in progress“there is mischief afoot”, “plans are afoot”, “preparations for the trial are underway”

Adverbs

(r)afooton foot; walking“they went to the village afoot”, “quail are hunted either afoot or on horseback”