Definitions of Yoga

I practice Hot yoga more than other practices just because that is what has my interest. Sometimes when I had a very stressful day and don't feel like sweating and dying I'll do something that is more on the meditation, spiritual side. During the Hot yoga I feel like yoga isn't being defined at all as it is in the other classes I have taken. I would say that it is defined as breathing and spirituality whereas hot yoga you arent really focusing on that, you are more focused on not dying. Well i am atleast.