sagless
Without any droop
Sagless means without sagging—maintaining firmness or tension where drooping might be expected.
The word appears most often in advertising for mattresses, upholstery, and undergarments: sagless springs, sagless support.
It's a commercial coinage rather than natural speech.
Solid or resolute
- tautStretched under tension
- rigidUnable to bend
- sturdySolidly built, durable
- supportiveOffering help and reassurance
unyielding · stable · tight · secure · snug · reinforced · braced · tensioned
Able to withstand use
- resilientAble to recover quickly
- long-lastingPersisting over extended time
- hard-wearingResistant to damage
- robustStrong and durable
tough · elastic · springy · buoyant · resistant · high-density · tempered · reinforced
firm
Solid or resolute
supportive · unyielding · stable · tight · secure · snug · reinforced · braced · tensioned · stretched
durable
Able to withstand use
- resilientAble to recover quickly
- long-lastingPersisting over extended time
- hard-wearingResistant to damage
robust · tough · elastic · springy · buoyant · resistant · high-density · tempered · reinforced · quality
mattress
Padded sleeping surface
- cushionStuffed fabric for comfort
- upholsteryFurniture's textile layer
- couchUpholstered seating furniture
sofa · springs · padding · foam · webbing · slats · box-spring · seat · hammock · recliner
smooth
Without roughness or difficulty
sleek · trim · toned · perky · lifted · youthful · fresh · unwrinkled · unlined · contoured