a quadrangle

students greeted him as he walked through the quad

a quadruplet

9,294 women gave birth to twins, while 147 had triplets, and five had quads

a quadriceps muscle

I have well-developed quads but my glutes are not all they could be

a quad bike

inexperienced riders on quads and mopeds

quadraphony

we issued records in two forms at once, stereo and quad

(in telephony) a group of four insulated conductors twisted together, usually forming two circuits

a radio aerial in the form of a square or rectangle broken in the middle of one side

a traditional four-wheeled roller skate

a small metal block in various sizes, lower than type height, used in letterpress printing for filling up short lines

quadruple or quadraphonic