Wiktionary
n. The wire that touches the crystal in a crystal radio.
Usage examples of "cat's whisker".
It had at least five times the range of the old spark gap transmitters and much better sensitivity than coherers or even the newer cat's whisker receivers.
Amazing as it is to me, being clean as a cat's whisker has distinct advantages.
Simon recalled a book he had once read about the great Houdini, and how that now legendary fellow could find his way out of a locked safe with little more than a cat's whisker and a piece of crystal to aid him.
Not even a cat's whisker of difference, but people like this, as competitive as any athletes could ever be, worked damned hard for that fifth of a percentage point, and it really came down to who'd had what for breakfast on the mornings of the competitive exercises, or maybe what they'd dreamed about doing the night.
He placed himself at the table, strapped the set of earphones over his head, and began dipping the cat's whisker against the crystal.
So he left the cat's whisker where it was and began slowly running the bead along the tuning coil.