vacuous (adj.)

• airy
• asinine
• awkward
• bare
• barren
• bland
• blank
• bleached
• callow
• calm
• catchpenny
• characterless
• clear
• devoid
• dumb
• empty
• empty-headed
• fatuous
• featureless
• flimsy
• foolish
• frivolous
• frothy
• futile
• gauche
• green
• groping
• hollow
• idle
• ignorant
• inane
• inexperienced
• innocent
• insipid
• jejune
• lacking
• light
• minus
• missing
• naive
• negative
• nescient
• nonexistent
• nugatory
• null
• oblivious
• otiose
• passive
• rattlebrained
• raw
• relaxed
• scatterbrained
• shallow
• silly
• simple
• slender
• slight
• superficial
• tentative
• thoughtless
• tranquil
• trifling
• trite
• trivial
• unacquainted
• uncomprehending
• unenlightened
• unfamiliar
• unilluminated
• uninformed
• uninitiated
• unintelligent
• unknowing
• unoccupied
• unreasoning
• unrelieved
• unripe
• unsure
• unthinking
• unversed
• vacant
• vain
• vapid
• void
• white
• windy