Denture stability refers to the ability of the denture to resist horizontal or lateral forces during function without displacement. It is distinct from retention, which primarily concerns resistance to vertical dislodging forces. Stability ensures the denture remains steady during mastication and speaking, preventing rocking or tipping movements. This is achieved through proper extension, adaptation to the residual ridge, and occlusal harmony. Therefore, resistance to horizontal dislodging forces is the key factor defining denture stability.

Reference: Prosthodontics, Ashish D. Kale, 2nd Edition.