tertium quid /tûrˈsh(i-)əm kwid or terˈti-ŭm/)

1. A third unknown thing related to two specific known things
2. Something intermediate between opposites
3. The third person in the eternal triangle

• bone
• bone-ache
• bone ash
• bone-bed
• bone-beds
• bone-black
• bone-breccia
• bone-cave
• bone-caves
• bone china
• boned
• bone-dry
• bone-dust
• bone-earth
• bonefish
• bonefishes
• bonehead
• bone-headed
• boneheads
• bone-idle
• bone-lace
• boneless
• bone marrow
• bone marrow grafting
• bone marrows