Boyd’s Bible Dictionary:
(daily). An instrument for telling the time of day (2 Kings 20:11; Isa. 38:8).
Concise Bible Dictionary:
Some contrivance, not definitely specified, by which the divisions of the day were ascertained by the shadow of some gnomon or pillar, caused by the sun falling upon a series of steps or degrees (2 Kings 20:8-11 and Isa. 38:8). Hezekiah asked that the shadow might go backward ten degrees, and this took place on the dial of Ahaz. The same thing may not have occurred elsewhere, as it was simply to strengthen the faith of Hezekiah, nor is it necessary to suppose that the motion of the earth was reversed. May not the phenomenon have been produced by a peculiar state of the atmosphere causing refraction of the light passing through it? In whatever way it was brought about, it was by the power of God. Apparently a report of it reached Babylon, and ambassadors from the princes were sent to inquire of the “wonder” that had occurred (2 Chron. 32:31).
Modern Sundial