何一つ (nanihitotsu) Japanese meaning: (not) one | KotomoraThere is not a single problem.
He didn't know a single thing.
Usage patterns
何一つ〈動詞〉ないto not do/have a single (thing) of a certain kind
He doesn't know a single thing about the matter.
何一つ変わらないnothing at all has changed
Even after ten years, nothing about this town has changed at all.
〈場所〉に何一つ〈物〉がないthere isn't even a single (thing) in a place
In the emptied room, not a single thing was left behind.