hollowvow
nounUK /ˈhɒləʊvaʊ/
US /ˈhɑːloʊvaʊ/
A promise that someone does not really mean to keep.
He made a hollowvow to help, but he never showed up.
OTHER MEANINGS
2. A solemn-sounding commitment that is actually meaningless.
The treaty turned out to be a hollowvow that no one honored.
3. Words spoken to comfort someone without any intention of acting on them.
Her apology was a hollowvow, and everyone knew it.
4. A ritual or ceremonial pledge made without sincere belief.
The knights recited a hollowvow before the empty throne.