intellectual

[1]	intellect
[2]	thinker , intellect , highbrow , mastermind , genius , (Colloq) brain , egghead
[3]	scholar , academician , professor , savant , sage , wise man , guru , polymath , pundit , authority

adj.

[1]	mental , cerebral
[2]	thoughtful , rational , noetic , thought-provoking , highbrow , academic , bookish , scholarly , (Colloq) brainy
[3]	cerebral