radio, television, TV, video
cable, digital, satellite, terrestrial
commercial, independent
film (esp. BrE), movie, news, sports, etc.
pay-per-view

change, flip (AmE), flip through (esp. AmE), switch
I changed channels when the news came on.

change to, switch over to (esp. BrE), switch to, tune in to, tune to
watch
He was watching the cartoon channel.

surf
Lily surfed the channels on the television.

launch
Last year, the company launched its own TV channel.

broadcast
This channel broadcasts 24 hours a day.

on a/the channel
There's an interesting documentary on Channel 9 tonight.

direct, indirect
Journalists always have indirect channels for getting information.

formal, official
She first tried to get a doctor's certificate through official channels.

informal
appropriate, conventional, normal, proper, right, usual
effective
an effective channel for communication

diplomatic
communication, distribution
worldwide distribution channels

go through, use
If you want a visa, you will have to go through the proper channels.

establish, open, open up
attempts to open up new channels of communication

through a/the channel
The government hopes to settle the dispute through diplomatic channels.

a channel of communication
channels of distribution

deep
narrow
drainage, irrigation
Irrigation channels supply the crops with water.

river, water
The garden has fountains and water channels.

shipping

form
block