Where does “boardroom” come from?

I notice the etymological chain provided shows only English sources with repetitive cycling between "back," "backboard," and "room," which doesn't constitute a meaningful etymology tracing the word to an earlier language origin. Without a proper chain showing earlier language sources or a known meaning for "boardroom," I cannot write an accurate one-sentence etymology summary following the rules provided. Could you verify the etymological chain? A proper chain should show progression through different languages (e.g., English → Old English → Proto-Germanic, etc.) and ideally include the earliest known forms and their meanings.

boardroom (English): The room where a group of people conducts its...

Definitions

  1. The room where a group of people conducts its...

Ancestry of “boardroom”, step by step

boardroom traces back through two separate lines of ancestry.

via English board

StepLanguageWordMeaning
1EnglishboardA relatively long, wide and thin piece of any...
2Englishboardridersurfer
3EnglishriderOne who rides, often on a horse or a motorcycle;...
4Middle EnglishridereAlternative form of ryder
5Middle EnglishryderA rider or equestrian; one who rides a horse; A...
6Old Englishrīdererider, knight
7Old Englishrīdanto ride
8Proto-West Germanicrīdanto ride
9Proto-Germanicrīdanąto ride
10Proto-Indo-Europeanrēydʰ-
11Proto-Indo-Europeanh₂er-to fit, to fix, to put together

via English room

StepLanguageWordMeaning
1EnglishroomOpportunity or scope; Space "for" something, or...
2Middle EnglishroumA space or area; A room
3Old Englishrūmroom, space; roomy, spacious, ample, extensive,...
4Proto-West Germanicrūmroomy, spacious; room, open space
5Proto-Germanicrūmazroomy, spacious, open
6Proto-Indo-Europeanrewh₁-free space
Every word from Proto-Indo-European h₂er-Every word from Proto-Indo-European rēydʰ-Every word from Proto-Germanic rīdaną