As a Noun:
1. Partly digested food and drink that has come back up from someone's stomach and out through their mouth. English = vomit. Informal English = chunder.
2. The act of ejecting food and drink from your stomach and out through your mouth, usually because you are ill. English = vomiting.
As a Verb or Adjective:
1. To have food and drink come back from your stomach and out through your mouth, usually because you are ill. English = vomit, (be) sick. Idiomatic English = throw up. Informal English = chunder.