조심하다 [ josimhada ]
조심하다 is a verb and it mainly means ‘to be careful of (how to talk or how to behave)’ with 말 (‘words’. [ mal ]) or 행동 (‘behavior’. [ haengdong ]).
사람은 항상 말을 조심해야 한다. (One should be always careful of one’s language.)
행동 조심해, 철수야! (Behave, Cheolsu!)
But, 조심하다 is used more widely with other nouns such as body (몸), health (건강), things or situations, or someone else.
건강 조심하세요. (Take care of yourself, please.)
차 조심해. (Watch out for cars.)
엄마 오늘 기분 안좋아. 오늘 특히 엄마 조심해. (Mom is not happy today. Be careful with mom especially today.)