THC-O is the acetate ester type of THC, often called THC acetate ester or O-acetyl-Δ9-THC. It's generally called THC-O acetate (or ATHC or THC-Oa) among experts. However, it has been reduced by almost everyone to THC-O. Sometimes people go down the hyphen and call it THCO or THC O. However, you decide to spell it; it's pronounced "THC-oh"-- that's the letter O, not a zero. There are...