— watertightness , n.
/waw"teuhr tuyt', wot"euhr-/ , adj.
1. constructed or fitted so tightly as to be impervious to water: The ship had six watertight compartments.
2. so devised or planned as to be impossible to defeat, evade, or nullify: a watertight contract; a watertight alibi.
[ 1350-1400; ME; see WATER, TIGHT ]