noun, na-adjective, noun which may take the genitive case particle 'no'
eternity; permanence; perpetuity
Used for something lasting forever or indefinitely. Can be used as a noun, na-adjective, or no-adjective.
この世界に永久の平和は訪れるのだろうか。
Will eternal peace ever come to this world?
彼は永久にこの街を去った。
He left this town forever.
noun
Eikyū era (1113.7.13-1118.4.3)
Historical Japanese era name. Rarely used outside historical contexts.
永久の改元は1113年に行われた。
The change of era to Eikyū took place in 1113.