noun
marriage vows; pledge of eternal love
A poetic or literary term for a vow of lifelong commitment between lovers, often implying a promise to be together in the next life as well. Compare with 二世の約束, which is more common.
See also: 二世の約束
二人は二世の固めを交わした。
The two exchanged vows of eternal love.
Compound of 二世 (nise, 'two lives' or 'next life') and 固め (katame, 'hardening' or 'pledge'), literally 'pledge for the next life'. The exact historical derivation is uncertain, but it is a fixed expression in classical and literary Japanese.