Are brown dwarfs which don't sustain any fusion considered stars? I was reading about the coolest stars, and was surprised to find about stars with a surface temperature lower than a candle, like 2MASS 0939-2448 A/B, of about 100 Celsius like CFBDSIR 1458+10B and even below 0 Celsius temperature where the water freezes like WISE J0855-0714. Then I thought, they might be stars where fusion only happens very deep in the core, and then I found out this:
Brown dwarf

In addition, many brown dwarfs undergo no fusion; those at the low end
of the mass range (under 13 MJ) are never hot enough to fuse even
deuterium, and even those at the high end of the mass range (over 60
MJ) cool quickly enough that after 10 million years they no longer
undergo fusion.

Are these brown dwarfs which don't sustain any type of fusion considered stars? If so, what's the reason?
Brown dwarfs are technically stars, but not in your typical sense, as they cannot start or sustain nuclear fusion. Think about it this way: stars are formed in clumps inside giant gas clouds called nebulae, along with planets, but what if one of these clumps is too big to become a planet and too small to become red dwarfs. These are brown dwarfs. Some consider them to be stars, others consider them to be planets, and some neither. So, opinions vary.