take off one's hat to, to

To express admiration; a form of applause. Doffing one’s hat was long a mark of deference or respect, and to some extent it still is, even now that hats are no longer standard attire. The figurative use of the term dates from the mid-nineteenth century. In 1886 Harper’s Magazine stated, “We should take off our hats to them and wish them godspeed.”