telltale

One who informs on another; a talebearer.

Something that indicates or reveals information; a sign.

Any of various devices that indicate or register information, especially.

A time clock.

One of the brightly colored lengths of yarn or ribbon attached to the shrouds, stays, or sails of a sailboat, serving to indicate wind direction relative to the boat’s motion.

A row of strips hung above a railroad track to warn a passing train of low clearance ahead.

A resonant metal strip, 24 or 30 inches (61 or 76 centimeters) high, across the bottom of the front wall of a racquets or squash court above which the ball must be hit.

One who officiously or heedlessly communicates information concerning the private affairs of others; one who tells that which is supposed to be secret or private; a blabber; an informer; a tale-bearer.

An indication or an indicator; that which serves to convey information.

A name given to a variety of instruments or devices, usually automatic, used for counting, indicating, registering, or otherwise giving desired information.