dowse
Concise Oxford English Dictionary © 2008 Oxford University Press:
dowse /daʊz/
▶verb (usu. as noun dowsing) search for underground water or minerals by observing the motion of a pointer, supposedly in response to unseen influences.
– derivatives
dowser noun.
dowser noun.
– origin C17: of unknown origin.
'dowse' also found in these Oxford entries:

