Allow someone to achieve an end in his or her own way. The term comes from horseback riding, where since the sixteenth century a horse has been said to be given its head when the rider loosens the reins and lets it go where it will. It had been transferred to human beings by about 1700, as it was in Richard Steele’s play The Tender Husband (1703, 1.1): “What a fool I have been to give him his head so long.”