say it: HED-ur
header is a noun meaning "a line of text serving to indicate what the passage below it is about". It carries 7 recorded senses.
a framing member crossing and supporting the ends of joists, studs, or rafters so as to transfer their weight to parallel joists, studs, or rafters
a machine that cuts the heads off grain and moves them into a wagon
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 header 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.