The Collaborative International Dictionary of English v.0.48:

Broadcast \Broad"cast`\, n.
   1. (Agric.) A casting or throwing seed in all directions, as
      from the hand in sowing.
      [1913 Webster]

   2. an act of broadcasting; specifically, a program in which
      sounds or images are transmitted in all directions from a
      radio or television station; -- usually referring to a
      scheduled program on a commercial or public service radio
      or television station, using the normal radio frequencies
      for those media, in contrast to a radiotelephone
      conversation, which may also be transmitted in all
      directions, but is intended for receipt by a base station
      in the telephone network.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Broadcast \Broad"cast`\, a.
   1. Cast or dispersed in all directions, as seed from the hand
      in sowing; widely diffused.
      [1913 Webster]

   2. Scattering in all directions (as a method of sowing); --
      opposed to planting in hills, or rows.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Broadcast \Broad"cast`\, adv.
   So as to scatter or be scattered in all directions; so as to
   spread widely, as seed from the hand in sowing, or news from
   the press.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Broadcast \Broad"cast`\, v.
   1. to cast or disperse in all directions, as seed from the
      hand in sowing; to diffuse widely.
      [1913 Webster]

   2. to transmit (sounds, images, or other signals) in all
      directions from a radio or television station.
      [PJC]

   3. to disseminate (information, a speech, an advertisement,
      etc.) from a radio or television station.
      [PJC]

   4. to spread (information, news, gossip) widely by any means.
      [PJC]

WordNet (r) 3.0 (2006):

broadcast
    n 1: message that is transmitted by radio or television
    2: a radio or television show; "did you see his program last
       night?" [syn: broadcast, program, programme]
    v 1: broadcast over the airwaves, as in radio or television; "We
         cannot air this X-rated song" [syn: air, send,
         broadcast, beam, transmit]
    2: sow over a wide area, especially by hand; "broadcast seeds"
    3: cause to become widely known; "spread information";
       "circulate a rumor"; "broadcast the news" [syn: circulate,
       circularize, circularise, distribute, disseminate,
       propagate, broadcast, spread, diffuse, disperse,
       pass around]

The Free On-line Dictionary of Computing (19 January 2023):

broadcast

   A transmission to multiple, unspecified recipients.  On
   Ethernet, a broadcast packet is a special type of multicast
   packet which all nodes on the network are always willing to
   receive.