(rail transport) A railway signal controlling entry to the next section of line. Originally it meant a signal governing entry into a station.

(rail transport) Synonym of starting signal.

(rail transport, British spelling) An electric railway signal with colour aspects, showing either red or green in a 2-aspect signal, with the addition of a yellow or double yellow aspect (meaning caution) in 3- and 4-aspect signals.

(rail transport) A railway signal controlling the starting of trains from a station or some other location, nowadays usually a colour-light signal. / (sports) A signal to begin a race.

plural of signalee

(rare) The person toward whom a signal is directed.

plural of signal check

(rail transport) An instance where a train must stop at a red signal, or slow down before passing a signal displaying a yellow aspect.

(rail transport, UK) A signal given to a train driver by the guard of the train, or a member of station staff, that the train is ready to depart.

(probability) Having a p-value of 0.05 or less (having a probability 5% or less of occurring by random chance; less than 1 chance in 20 of it occurring by chance) / Pertaining to statistical significance