Slow-witted, stupid.

(dated, technical) Light bulb.

an arrangement by which a sidewalk is extended outwards for a bus stop

a type of lightbulb that mimics the appearance of bulbs and filaments and light produced by early light bulbs of Edison General Electric during the introductory period of electric lighting

(anatomy) The enlarged proximal part of the corpus spongiosum.

The end of the hair follicle under the skin, in which there are cells that grow hair

(meteorology) Cooling caused by evaporation.

Relating to wet-bulb temperature measurements.

Alternative form of not the brightest bulb in the chandelier.

Any joke of the form "How many X does it take to change a light bulb?" followed by a witty riposte, where X is some usually stereotypical class of people.