stumper

One day I sailed safely through a problem that was noted as a regular stumper.

Enough was a complete stumper, because there was no f in it.

That was a "stumper" for the poor woman, who evidently did not understand one-half of the sentence.

It wur a stumper to Sally, so she got Jess to explain it, and the way he did it was enormous.

That was a 'stumper' for the poor woman, who evidently did not understand one half of the sentence.