keystone

As nouns the difference between keystone and headstone

is that keystone is (architecture) the top stone of an arch while headstone is a gravestone, a grave marker: a monument traditionally made of stone placed at the head of a grave.

As nouns the difference between keystone and anchor

is that keystone is (architecture) the top stone of an arch while anchor is (label) a tool used to moor a vessel to the bottom of a sea or river to resist movement.

As a verb anchor is

to hold an object, especially a ship or a boat to a fixed point.

As nouns the difference between datum and keystone

is that datum is date (point of time at which a transaction or event takes place) while keystone is (architecture) the top stone of an arch.

As nouns the difference between keystone and donkey

is that keystone is (architecture) the top stone of an arch while donkey is a domestic animal, , similar to a horse.

As nouns the difference between keystone and mainspring

is that keystone is (architecture) the top stone of an arch while mainspring is the principal spring of a clockwork mechanism, that drives it by uncoiling.

As nouns the difference between keystone and drystone

is that keystone is (architecture) the top stone of an arch while drystone is (geology) a stalactite or stalagmite.

As an adjective drystone is

.

As nouns the difference between boss and keystone

is that boss is boss (person in charge, supervisor) while keystone is (architecture) the top stone of an arch.