tough as an old boot

*tough as an old boot and *tough as old (shoe) leather 

1. [of meat] very tough. (*Also: as ~.) This meat is tough as an old boot. Bob couldn't eat the steak. It was as tough as an old boot.

2. [of someone] very strong willed. (*Also: as ~.) When Brian was lost in the mountains, his friends did not fear for him; they knew he was tough as leather. My English teacher was as tough as an old boot.

3. [of someone] not easily moved by feelings such as pity. (*Also: as ~.) She doesn't care. She's as tough as old shoe leather. He was born tough as an old boot and has only grown more rigid.

See also: boot, old, tough