jackstone
[
jak
-stohn]
/ˈdʒækˌstoʊn/
noun
1.
jack
1
(def 5a, b).
2.
jackstones,
(
used with a singular verb
)
jack
1
(def 5c).
Origin
1805-15;
earlier
chackstone,
alteration of
checkstone
pebble, of uncertain origin