Featherbrained means extremely silly — as if someone's brain were as light as a feather, with nothing solid inside. It is an unkind word, a little old-fashioned, and more for books than for kind conversation. If you say it about a person, you are calling them empty-headed. Scatterbrained is a neighbour word, but it is not the same: scatterbrained people forget things and jump from idea to idea; featherbrained leans more toward not thinking well. In class, silly or careless is a kinder choice.

沒頭腦的（過時、帶貶義）