In a way that is unnecessary; doing something without any real reason or purpose.
From 'needless' (without need) plus '-ly' (adverb suffix). 'Need' comes from Old English 'nyd' meaning urgent necessity.
It's fascinating that we say 'needlessly' but not 'greedlessly' or 'speedlessly'—English adds -less to create adjectives, but the adverb form works best with words already meaning lack or absence.
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