Wanting in energy, force, or effect. of the mind, thoughts, etc.

Lacking force of intellect or strength of mind; easily deceived, credulous.

(un-, prefix1 affix 1.)

figurative. Of thought, reasoning, observation, knowledge, or feeling: Lacking depth, superficial.

(un-, prefix1 affix 1.)

Not profound; shallow, superficial.

figurative. Of intellect, etc. (Cf. shallow, adj.1 6.)

Of ideas, the mind, etc.: unsound, lacking rigour.

Of the mind: Weak, disordered.

Not excursive; incapable of a wide range of flight.

Having, or regarded as having, little or no intellectual or cultural value; demanding or involving very little intellectual application.