I didn't know this word but it was the last answer in yesterday's crossword. The cryptic clue was
Line showing equal water depth is over tub (7)
This baffled me but a friend suggested the word play is IS + O + BATH = ISOBATH (tub is 'bath', get it?) and there must therefor be such a word. Sure enough when I looked up isobath it means a line of equal water depth. Merriam-Webster gives the definition as:
an imaginary line or a line on a map or chart that connects all points having the same depth below a water surface
As well as this meaning the OED provides a second definition, for a special kind of inkwell:
Trade-name for an inkstand with a float so contrived as to keep the ink in the dipping-well at a constant level
Ingenious but I suppose largely obsolete.
Since water is involved is there any connection with baths? Well no, isobath is from Latin and Greek. iso means 'the same', in Latin/Greek as in isobar or isotherm, and the bath element means 'deep' in Greek, as in bathysphere. Bath on the other hand is an English word of Germanic descent and comes from a root that originally had connections with warming, so applying the word bath to hot springs is very appropriate. German Bad meaning bath is essentially the same word.
Meet the Isobaths
I didn't know this word but it was the last answer in yesterday's crossword. The cryptic clue was
Line showing equal water depth is over tub (7)
an imaginary line or a line on a map or chart that connects all points having the same depth below a water surface
As well as this meaning the OED provides a second definition, for a special kind of inkwell:
Trade-name for an inkstand with a float so contrived as to keep the ink in the dipping-well at a constant level
Ingenious but I suppose largely obsolete.Since water is involved is there any connection with baths? Well no, isobath is from Latin and Greek. iso means 'the same', in Latin/Greek as in isobar or isotherm, and the bath element means 'deep' in Greek, as in bathysphere. Bath on the other hand is an English word of Germanic descent and comes from a root that originally had connections with warming, so applying the word bath to hot springs is very appropriate. German Bad meaning bath is essentially the same word.