Related Clues:

• Like some stomachs
• Rigid
• More than strong
• Not subject to change
• Able to withstand great strain
• Airtight
• Skillet makeup
• Like some alibis
• Like a good alibi
• Flawless
• Leakproof
• Unbreakable, as a contract
• Molded metal
• Unconquerable
• Like an inflexible agreement