the world > space > relative position > support > [noun] > that which supports > support of specific shape (4)
Something shaped like a stirrup. A U-shaped clamp or support.
A contrivance or piece of apparatus in the form of the letter Y; esp. a forked support for a telescope, theodolite, or piece of mechanism.
(See quots. and cf. Y, n. 3.)
In plural. Two crossed supports pivoted like the two halves of a pair of scissors.