o'cool Share definition Flag used in subsitute of ok. Meaning that you are more in favour then just "ok". A postive term "yeh thats o'cool with me" nobody liked my haircut but i was o'cool with it. o'cool by Matthew_aatikitoo July 30, 2008 0 0 Get merch Get the o'cool mug. Buy Now — $32.95 See more merch