Cast about verb – Search anxiously. Forage and cast about are semantically related in look topic. In some cases you can use "Forage" instead a verb "Cast about", when it comes to topics like seek to find something.
Forage verb – To feed on grass or herbs. Cast about and forage are semantically related in hunt topic. You can use "Cast about" instead a verb "Forage", if it concerns topics such as search, search madly for.