Having no cost; free or without payment required.
From 'cost' plus the suffix '-less' (without). A direct formation meaning without cost, formed using the productive English suffix that also appears in 'homeless,' 'helpless,' and similar negation formations.
The word 'free' already means costless, yet we invented 'costless' anyway—sometimes language generates synonyms unnecessarily, perhaps because different words feel different even when they mean the same thing.
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