On foot. (means of locomotion, walking) / On foot. (support of the body, standing) / (figuratively) In motion; in action; astir; stirring; in progress.

One who studies crustaceology.

In an unceremonial manner, abruptly, without the due formalities.

(informal) Resembling vomit in colour, texture, etc. / (informal) Inclined to vomit; sick.