a boulder so delicately poised that it can be rocked
Also called: logan, logan-stone
rocking stone in American English
noun
any fairly large rock so situated on its base that slight forces can cause it to move or sway
Also called: logan stone, loggan stone, logging stone
Word origin
[1730–40]This word is first recorded in the period 1730–40. Other words that entered Englishat around the same time include: bronze, humbug, maximum, optimism, secret service