retarded

Delayed; delayed in development, hindered; impeded.

This kind of plant is usually of a retarded growth.

The last zone, lying beyond the Ch‘ang-pai mountains, was in special isolation and culturally as retarded as regions much farther north.

Having mental retardation; mentally deficient or underdeveloped.

Experts in the field say there are now at least 200,000 retarded people over 60 in the United States.

One day the order of things begins to unravel. First, the doctor, on horseback, is tripped up by an invisible wire and his injuries put him in the hospital for months. Then several children, including the son of the Baron and the retarded child of the doctor’s mistress, are severely beaten. Later, the Baron’s barn is set on fire.

Specifically, having an IQ below 70.

Extremely stupid; obtuse

Looking at Jack, Gabbie said, "What?" "That's the Troll Bridge." She groaned at the pun. "That's retarded."

I've got a terrific sign in front of my house that keeps intruders out: Retarded Pit Bull High on Angel Dust. No one's come over the wall yet. Except a couple of retarded guys who were high on angel dust.

Designating a parameter of an electromagnetic field which is adjusted to account for the finite speed of radiation.