Without a flag or lacking flags; not having a flag to represent or signal.
From English 'flag' (a piece of cloth used as a symbol) plus the suffix '-less' (meaning without), which comes from Old English '-lēas'. The combination literally means 'without a flag.'
The suffix '-less' is one of the most productive word-building tools in English—you can add it to almost any noun to create an adjective meaning its opposite, which is why 'flagless' feels instantly understandable even if you've never heard it before!
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