These statements provide a quick tip sheet for describing Intellectual Giftedness.

https://www.sciencedaily.com/terms/intellectual_giftedness.htm

Science Daily presents a wide variety of articles, appealing to a broad array of interests, from a vast number of sources, and does so in easy-to-understand layman's terms.

To the Science Daily list, I would add the following detail and clarification:
... a pioneering Polish psychiatrist, Kazimierz Dabrowski, catalogued such personality traits in a cluster that translates from the Polish as “superstimulatability” or “overexcitability.”

The five traits he identified are:
1- an abundance of physical energy;
2- sensory hyper-reactivity;
3- vivid imagination;
4- intellectual curiosity and drive; and
5- a deep capacity to care.
The combination of all five manifests as an emotional complexity and intensity.