the.com/waterproof
A promise from your gear that water keeps as long as you don't read the fine print.
means Built to keep water out entirely, as opposed to merely resisting it for a while.
from A plain English compound from water plus proof, where proof means tested-and-able-to-resist, the same sense lurking in bulletproof and foolproof.
Rating realityTrue waterproof carries an IP68 or depth rating; resistant means hope.
Legal nuanceMany countries ban marketing watches as waterproof, only water-resistant.
Original sealantEarly raincoats used rubber, hence the Mackintosh, named after its inventor.