brainless

Further away, the scientists found a cluster made up of brainless things, such as plants and free‐living bacteria.

Don't fancy that a man who has made millions—made it, understand—is brainless, and not well worth knowing.

He is utterly insignificant, rebuked, and humiliated,--even as a brainless beauty finds herself de trop in a circle of wits.

Especially he had despised the young men as brainless cowards in regard to their views of women and conduct toward them.