indissoluble

US /ˌɪn.dɪˈsɑːl.jə.bəl/
UK /ˌɪn.dɪˈsɑːl.jə.bəl/
1.

不溶性の

impossible to take apart or bring to an end, or existing for a very long time:

:
•
an indissoluble bond of friendship