say it: an-tee-ER-kraft
antiaircraft is a noun and adjective meaning "artillery designed to shoot upward at airplanes". It carries 2 recorded senses.
artillery designed to shoot upward at airplanes
designed for defense from a surface position against air attack
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 antiaircraft 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.