Empty
Vacant, Futile, Vain
い adjective
むなしい
いい加減 (いいかげん) Irresponsible, Pointless, Unfounded, Careless
無駄 (むだ) Futility, Uselessness, Pointlessness
虚しい (むなしい) Empty, Vacant, Futile, Vain
空疎 (くうそ) Vain, Groundless, Futile
無し (なし) Without, With No
Only someone with an Empty head would moon-a むな sheep しい