say it: kwahd
quad is a noun meaning "one of four children born at the same time from the same pregnancy". It carries 4 recorded senses.
one of four children born at the same time from the same pregnancy
a muscle of the thigh that extends the leg
(printing) a block of type without a raised letter; used for spacing between words or sentences
printing
a rectangular area surrounded on all sides by buildings
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for quad come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.