Structural crack
A crack that indicates the concrete is being overloaded or that the structure is moving, as opposed to a cosmetic crack from shrinkage or surface effects.
What does structural crack mean?
Warning signs include cracks that are wide, that pass through the full thickness, that offset or displace, that grow over time, or that appear in beams, columns, and walls rather than in slabs. Diagonal cracking near supports and horizontal cracking in a basement wall are particularly serious patterns. Evaluation belongs to a structural engineer, not to a repair contractor selling the repair.
In practice
Horizontal cracks in a foundation wall with the wall bowing inward are the pattern that warrants an engineer the same week.