I'm taking an intro communications module and I'm quite confused on what the term "symbol" really means?

Consider this setup:

My understanding is as folllows

1. After the information source, we have a stream of bits coming in 0 1 0 1 0 0 0 1 1.....
2. The source encoder takes these bits and groups them into sets of N bits.
3. The channel encoder takes these sets of N bits and based on what coding scheme we use (gray coding) for example, it will multiply it by a certain coefficient of a orthogonal basis function (carrier signal) depending on what exact gray code it is.
4. The digital modulator now receives a coefficient of it's carrier/basis function and just mulitplies it by the fixed carrier/basis function (either sin or cos of something) and sends it onto the channel.

My question is - what point in this transmitter do we call "the symbol"? Is it the group of N bits after the source encoder? Or is it the coefficient of the orhtogonal basis function after the channel encoder?