Hi VR00- 150 IQ is higher than the 99.5%. More like 99.9% and something past that. 150+ is verging on "profoundly gifted."
I think "gifted" in terms of "meaning" is subject to individual interpretation, while gifted in terms of "definition" is objective (at least as it applies to intellectual giftedness). It's typically an IQ of 130+ in US public schools. The top 98th percentile, give or take.
It's possible and common for children to be gifted in some areas, typical in others, and may even be lagging in some spots. The 130 IQ cutoff (full scale) is less informative than the subtest scores.