Webster's Revised Unabridged Dictionary · 1913

Intellectual

Intellectual (?; 135) , adjective

[Latin intellectualis: compare French intellectuel.]

1.
Belonging to, or performed by, the intellect; mental; as, intellectual powers, activities, etc.
Logic is to teach us the right use of our reason or intellectual powers. — I. Watts
2.
Endowed with intellect; having the power of understanding; having capacity for the higher forms of knowledge or thought; characterized by intelligence or mental capacity; as, an intellectual person.
Who would lose, Though full of pain, this intellectual being, Those thoughts that wander through eternity? — Milton
3.
Suitable for exercising the intellect; formed by, and existing for, the intellect alone; perceived by the intellect; as, intellectual employments.
4.
Relating to the understanding; treating of the mind; as, intellectual philosophy, sometimes called “mental” philosophy.

Intellectual , noun

1.
The intellect or understanding; mental powers or faculties.
Her husband, for I view far round, not nigh, Whose higher intellectual more I shun. — Milton
I kept her intellectuals in a state of exercise. — De Quincey
2.
A learned person or one of high intelligence;
one who places greatest value on activities requiring exercise of the intelligence, such as study, complex forms of knowledge, literature and aesthetic matters, reflection and philosophical speculation; a member of the intelligentsia; as, intellectuals are often apalled at the inanities that pass for entertainment on television.