HG Share definition Flag Highly gifted; having or possessing a demonstrated IQ of 145 or greater. That kid is totally HG, I saw him playing the piano and reading Dostoyevsky at the same time. And then he murmored something witty to me. HG by Daniel Vincent April 30, 2006 0 0 Get merch Get the HG mug. Buy Now — $32.95 See more merch