The only additional part of defining "near field" listening that I'd add is: your listening position is equal to or less than the distance between the speakers themselves. For example, if your speakers are 9 feet apart, a "near field" listening position is 9 feet or less from the front of the speakers.
What is "Near Field" listening?
My speakers are 6 ft. apart and 7 ft. from my sitting position. I have stand mount monitors with a 50 watt amp. I'm fairly new to this. This set up seems to give me the best sound. BTW, the speakers are 3.5 ft. from the front wall with about 15 feet on either side. There is another 8 ft. behind me. It sounds pretty good and I'd like to quit moving them and just listen. What do you think?