noun 1.something that leads in or introduces; introduction; opening.
2.Radio, Television.a.the connection between an antenna and a transmitter or receiving
set.
b.the portion of a program or script that precedes or introduces a commercial.
adjective 3.(of a conductor) carrying input to an electric or electronic device or circuit, especially from an antenna.
Origin:
1910–15; noun, adj. use of verb phrase lead in