The glossaries seem to be the best place for the definitions of the terms on this page.

True Source#

"The driving force of the universe, which turns the The Wheel of Time. It is divided into a male half (saidin) and a female half (saidar), which work at the same time with and against each other. Only a man can draw on saidin, only a woman on saidar. Since the beginning of the Time of Madness, saidin has been tainted by the Dark One's touch." (The Eye of the World,Glossary)

One Power#

"The power drawn from the True Source." (The Eye of the World,Glossary)
More at One Power.

Channeling#

  1. (verb) To control the flow of the One Power (The Eye of the World,Glossary)
  2. (noun) The act of controlling the flow of the One Power. (The Eye of the World,Glossary)

The One Power comes from the True Source, the driving force of Creation. The male half of the True Source, saidin, and the female half, saidar, work against each other and with each other to provide the force that turns the Wheel of Time. The True Source cannot be used up just as a river cannot be used up by a mill wheel. (TEotW,Ch12)

Things Learned During The Series (Possible Spoilers)#

Five Powers#

"There are threads to the One Power, and each person who can channel the One Power can usually grasp some threads better than others. These threads are named according to the sort of things that can be done using them - Earth, Air, Fire, Water, and Spirit - and are called the Five Powers....While Spirit was found equally in men and in women, great ability with Earth and/or Fire was found much more often among men, with Water and/or Air among women." (The Eye of the World, Glossary)

Saidar and Saidin#

Pronunciation: sah-ih-DAHR, sah-ih-DEEN Content unavailable! (broken link)https://encyclopaedia-wot.org/attach/Pronunciation/soundbut.gif

Saidar is the female half of the True Source and saidin is the male half of the True Source. Only a man can draw on saidin, only a woman on saidar. Saidin is fouled by the taint of the Dark One, like a thin slick of rancid oil on water. The water is still pure, but it cannot be touched without touching the foulness. (TEotW,Ch12) Their bonds, oaths and ties to the Great Lord protect the male Forsaken from the taint. (TFoH,Prologue)

Gentling/Stilling#

Gentling is

"the act, performed by Aes Sedai, of shutting off a male who can channel from the One Power...A man who has been gentled can still sense the True Source, but he cannot touch it." (The Eye of the World,Glossary)

Stilling is

"the act, performed by Aes Sedai, of shutting off a female who can channel from the One Power...A woman who has been stilled can still sense the True Source, but she cannot touch it." (The Eye of the World,Glossary)

True Power (Possible Spoilers)#

Talents#

See Weaves.

Angreal, Sa'angreal, Ter'angreal#

See Angreal.