Without a chair; lacking seating or not having a chair to sit on.
From 'chair' + the suffix '-less' (meaning 'without'), which comes from Old English 'leas'. This is a straightforward combination meaning simply the absence of chairs.
The word 'chairless' is rarely used because most people just say 'no chairs' or 'no seating,' but it's a perfect example of how English lets us add '-less' to almost any noun to mean 'without it.'
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