adjective
staunch
STAWNCH/stɔːntʃ/
firm and loyal in support
He remains a staunch friend while another person criticizes her.

Etymology
Old French estanc meant 'watertight.' English moved from this physical sense to 'strong, substantial,' then applied the word to people who remain firm and true to their principles.
In context
the staunch unionist vehemently opposed to slavery established his agency in the 1850s
More examples
- She was a staunch defender of the library.
- The plan had several staunch supporters.
- Their staunch loyalty survived the difficult years.
Forms
staunch · more staunch · most staunch