A transmitter encodes data by producing a signal which is a continuous stream of signalling events each which has sufficient information for the receiver to recover the original data. Just like a quantum leap is the smallest measurable leap, a signalling event is the smallest possible amount of signal that the receiver needs to recover the original data without error.

An unclear message, often contradicting a situation.

(US, telephony) An audible signal to the calling party that indicates failure to complete the requested connection; an engaged tone

plural of traffic signal

plural of time signal

plural of time-signal

A building, typically adjacent to or spanning a railway line, from where signals, points and (sometimes) level crossings are controlled. / The alarm-box of a police or fire-alarm system.

plural of signal box

(endocrinology) A type of cell signaling involving the release of a hormone from a nerve cell that has an effect on another cell.

(biochemistry) A series of chemical reactions within a cell which start when a transmembrane protein comes into contact with a chemical signal, resulting in a second messenger being triggered.