Defect
Work that fails to comply with the contract or specification. Distinct from a snag (a minor completion-stage item) and from an NCR (a formal quality record raised during execution) — the three behave completely differently in contract.
A defect discovered after taking-over is managed under the defects liability regime: the contractor returns and remedies it. A defect discovered during execution is an NCR. A minor cosmetic item at handover is a snag. The words get used interchangeably on site and they are not interchangeable.
And the one that changes character is the systemic snag. Cracking traced to missing reinforcement is not a snag, whatever the punch list calls it — it is a defect with structural consequences, and it escalates into a different regime with different money attached.