"A thing which is hard but can be broken easily."

The word that means the same as the group of words "a thing which is hard but can be broken easily" is brittle.

• Brittle means easily broken or cracked.
• Resilient means able to recover quickly from misfortune or change.
• Impregnable means impossible to penetrate or overcome.
• Ambivalent means having mixed or contradictory feelings or thoughts about something.