radiolucent
adjective
ra·dio·lu·cent ˌrā-dē-ō-ˈlü-sᵊnt 
: partly or wholly permeable to radiation
radiolucent tissues
radiolucency
ˌrā-dē-ō-ˈlü-sᵊn(t)-sē
noun 
Word History
First Known Use
1917, in the meaning defined above
Medical Definition
radiolucent
adjective
ra·dio·lu·cent -ˈlüs-ᵊnt
: partly or wholly permeable to radiation and especially X-rays compare radiopaque