Health and medicine

• 낫다 - to get well, to recover
• 다치다 - To get injured, to get hurt

Disease and sickness

• 콧물 - snot (literally nose water)
• 감기 (感氣) - A cold
• 감기 걸리다 - To catch a cold
• 기침(하다) - a cough, to cough, to have a cough

Hospital

• 문병(하다) - A visit to a sick person, to pay a visit to a sick person
• 병 - Disease, illness
• 수술(하다) - Surgery, to operate on a patient
• 입원(하다) (入院) - Hospitalization, to be hospitalized
• 퇴원(하다) (退院) - Discharge from the hospital, to be discharged from the hospital

Misc

• 심하다 - TO be severe, to be serious