The small, soundless, almost imperceptible signal would be sent, whether he intended it to be or not.

Instead of an almost imperceptible signal, one server asked "everybody ready?"

Catching the eye of another man on the edge of the dance floor, Daniel gave a quick, almost imperceptible signal.

One of the professional bidders lounging against a wall flicked him an almost imperceptible signal, and he answered with another.

His eyes gave me an almost imperceptible signal, but I did not dare to look.

It caused the bartender to go into a reflective mood; then he gave an imperceptible signal to one of the thuggish customers, who immediately departed.

At an imperceptible signal from him, she held the bowl up and turned to face the clan.

But The Shadow saw the imperceptible signal that passed between Starr and the blond artist's model.

When they entered the compound, Lunzie was crossing from the shuttle to her quarters and gave Varian an imperceptible signal to join her.

An imperceptible signal passed between husband and wife, meaning that they grasped the situation and would stand by each other loyally.