unsprung
/ˈʌnsprʌŋ/Definitions
1. adjective
Not sprung or stiffened; not able to bear weight or pressure.
“The unsprung wheels of the old car made it difficult to steer.”
2. noun
A part of a vehicle’s suspension system that has not been sprung.
“The mechanic had to replace the unsprungs on the entire fleet of buses.”