solidity
noun [ U ] uk/səˈlɪd.ə.ti/ us/səˈlɪd.ə.t̬i/ (also solidness)
(FIRM)
固态;坚固
the quality of being hard or firm, not a liquid or gas
(CERTAIN)
坚牢，确实
the quality of being certain or strong
The agreement would give a new solidity to military cooperation between the two countries. 该协议将进一步巩固两国间的军事合作。