Used (though less commonly than "chair") meaning ‘to preside as chairman over a meeting or committee’.
Definitionen
To preside over (a meeting, committee, or event) as its chairman; to act as chair of. She will chairman tomorrow's panel discussion on renewable energy.
Attributive use of the noun: ‘of or relating to a chairman’.
Definitionen
Relating to, characteristic of, or held by a chairman. The chairman election was scheduled for July.