Moving or dancing rhythmically to music, or enjoying something with a relaxed, satisfied feeling.
From Dutch 'groeve' (furrow or groove), which entered English in the 1600s. The sense 'to move rhythmically' came later, possibly influenced by the idea of moving in a consistent groove or pattern.
The musical term 'grooving' became hugely popular in 1960s-70s funk and soul music, where getting 'into the groove' meant syncing with the rhythm so perfectly that the music and body moved as one unified force.
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